A method for studying the static and fatigue properties of a lateral stabilizer bar

Abstract

The present invention belongs to the technical field of automobile lateral stabilizer bars and relates to a method for studying the static and fatigue properties of lateral stabilizer bars. The present invention establishes a finite element model of the lateral stabilizer bar, verifies the accuracy of the stress and roll stiffness calculation of the numerical model under vertical load conditions through mechanical theoretical calculations and stiffness bench tests, and performs static strength analysis on the lateral stabilizer bar assembly under combined load conditions; on this basis, the road load spectrum is combined with component bench fatigue tests and virtual simulation technology to study the fatigue life of the lateral stabilizer bar.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile lateral stabilizer bars and relates to a method for studying the static and fatigue properties of lateral stabilizer bars. Background Art

[0002] The automobile lateral stabilizer bar (hereinafter referred to as "stabilizer bar"), also known as anti-roll bar or balance bar, is an auxiliary elastic element in the automobile suspension. When turning or in poor road conditions, the body of the car will tilt and vibrate laterally due to the relative reverse bounce of the suspension on both sides. The ends of the thrust rods on both sides cause the stabilizer bar to generate torsion through relative vertical displacement, and the elastic force of the rod body prevents the wheels from lifting, so that the body can be kept balanced as much as possible and the driving comfort and stability can be improved. Relevant statistics show that fatigue fracture damage in engineering practice accounts for 50% to 90% of all mechanical damage, which is the most common form of mechanical and structural failure. Once fatigue problems occur, the reliability and service life of the mechanical system will be greatly reduced. When the suspension bounces on both sides are inconsistent, the lateral stabilizer bar body and thrust rod will be subjected to alternating torsion and bending respectively, which is prone to fatigue damage, so it is necessary to design the fatigue life of the lateral stabilizer bar reasonably.

[0003] Domestic and foreign scholars have conducted many studies on the fatigue life prediction and analysis of the lateral stabilizer bar. Liu Shuhui et al. completed a rapid evaluation of the durability of the stabilizer bar by combining fatigue simulation analysis with experimental testing; Mariusz et al. obtained the torsion angle of the lateral stabilizer bar through bench and real vehicle tests, used the obtained data as the input of fatigue analysis, and analyzed the influence of different stress levels on fatigue life; Palma et al. proposed the correlation between laboratory tests and road vehicle tests of stabilizer bars under different road surfaces and vehicle speeds, and determined the failure criteria of stabilizer bars under laboratory conditions; WITTEK et al. studied the influence of production process and material factors on the fatigue strength of stabilizer bars through metallographic analysis, hardness and roughness measurement. The present invention studies the static strength, static stiffness and fatigue performance of the lateral stabilizer bar through the beam theory of material mechanics, finite element method technology and bench test technology. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for studying the static and fatigue properties of a stabilizer bar. The present invention establishes a finite element model of the stabilizer bar, verifies the accuracy of the stress and roll stiffness calculation of the numerical model under vertical load conditions through mechanical theoretical calculations and stiffness bench tests, and performs static strength analysis on the stabilizer bar assembly under combined load conditions; on this basis, the road load spectrum is combined with component bench fatigue tests and virtual simulation technology to study the fatigue life of the stabilizer bar. First, the target rain flow matrix of a test cycle in a mixed road section of the test track is converted into a single amplitude, sinusoidal fixed-frequency load, and then bench fatigue tests and fatigue simulation analyses are carried out respectively to obtain the test and simulation life under sinusoidal loads, and finally the random load of the road test is extracted as the input condition for fatigue simulation to predict the fatigue life of the stabilizer bar.

[0005] The present invention is achieved through the following technical solution: A method for studying the static and fatigue properties of a lateral stabilizer bar, comprising the following steps:

[0006] Step S1, establishing a finite element model of a lateral stabilizer bar;

[0007] Step S2, performing static strength analysis of the lateral stabilizer bar;

[0008] Step S3, calculating the roll stiffness of the lateral stabilizer bar;

[0009] Step S4, performing fatigue test and simulation analysis of the lateral stabilizer bar;

[0010] Step S5: Perform road spectrum load fatigue analysis on the lateral stabilizer bar.

[0011] On the basis of the above scheme, further, the specific operation of step S1 is as follows:

[0012] The stabilizer bar CAD model established in Catia is imported into the pre-processing software HyperMesh for geometric cleaning, meshing, unit quality inspection and assembly to obtain a stabilizer bar assembly finite element model. The stabilizer bar consists of a stabilizer bar body, a thrust rod, a rubber bushing and a clamp. The Mooney-Rivlin model is used to simulate the rubber bushing.

[0013] The finite element model is divided by tetrahedral mesh, which consists of 50881 units and 15753 nodes. Contact is established between the stabilizer bar body and the rubber bushing, and between the rubber bushing and the clamp; Tie binding constraints are used to simulate welding between the stabilizer bar body and the thrust rod, without considering relative sliding; and the bolt connection is simulated by combining beam elements and MPC constraints.

[0014] On the basis of the above scheme, further, the specific operation of step S2 is as follows:

[0015] S2.1. Conduct finite element analysis of static strength under vertical load;

[0016] S2.2. Perform theoretical calculation of static strength under vertical load;

[0017] S2.3. Perform finite element analysis of the static strength of the lateral stabilizer bar under combined loads.

[0018] On the basis of the above scheme, further, the specific operation of step S2.1 is as follows

[0019] The load size of the lateral stabilizer bar static analysis is obtained by sampling the maximum strain amplitude of the stabilizer bar through road durability test, and the maximum amplitude of the corresponding strain of the stabilizer bar when a vertical load of ±25KN is applied to the stabilizer bar on one side is obtained by bench test calibration; the y-direction movement freedom at the 8 bolt holes connecting the lateral stabilizer bar body and the vehicle body and the 6 degrees of freedom of the mounting hole at one end of the thrust rod are constrained, and a concentrated force of 25KN is applied at the loading end of the thrust rod to complete the definition of the boundary conditions of the stabilizer bar assembly.

[0020] The finite element model was solved using the Abaqus standard solver, and the calculation results were post-processed using META to obtain the maximum Mises stress at each position of the stabilizer bar.

[0021] On the basis of the above scheme, further, the specific operation of step S2.2, performing theoretical calculation of static strength under vertical load, is as follows:

[0022] S2.21. Select the two sections A and B in the finite element model of the lateral stabilizer bar and extract the maximum Mises stress at the two sections A and B;

[0023] S2.22. According to the actual bench test loading method of the stabilizer bar, simplify and establish the mechanical model, and perform theoretical calculations on the Mises stress at points A and B based on the beam theory of material mechanics;

[0024] S2.23. Compare the finite element calculation results and the mechanical theory calculation results at sections A and B. If the stress results of the two are close, the correctness of the finite element model is verified.

[0025] On the basis of the above scheme, further, the specific operation of step S2.3 is as follows:

[0026] The maximum vertical load of 25kN and the maximum lateral load of 5kN are applied to the finite element model of the lateral stabilizer bar at the same time, and the stress distribution of the lateral stabilizer bar under the combined load is obtained. By comparing it with the maximum stress of the stabilizer bar under the vertical load condition, the influence of the vertical load and the lateral load on the stress condition of the stabilizer bar is determined.

[0027] On the basis of the above scheme, further, the specific operation of step S3 is as follows:

[0028] S3.1. Perform finite element calculation of roll stiffness

[0029] The formula for roll stiffness is shown in the figure below.

[0030] in, T Generates torque for the stabilizer bar shaft, T=Fl , is the rotation angle of the cross section where the thrust rod and the stabilizer rod are welded; l To simplify the length of the thrust rod in the mechanical model, F is the vertical load, and w´ is the displacement of the position where the vertical load is applied in the finite element model;

[0031] S3.2. Perform lateral stabilizer bar roll stiffness bench test

[0032] The stiffness bench test is clamped according to the actual vehicle state. The clamping method is to fix one end of the thrust rod joint and rigidly connect the other end to the actuator according to the actual vehicle connection form; record the applied torque and the size of the sample roll angle, and use the least squares method to fit the roll stiffness curve of the measured data. According to the fitting effect, the accuracy of the finite element model is verified.

[0033] On the basis of the above scheme, further, the specific operation of step S4 is as follows:

[0034] S4.1. Conduct fatigue bench test on lateral stabilizer bar;

[0035] Conduct a fatigue bench test on the lateral stabilizer bar of the sample under the combined load to obtain the number of cycles when the sample breaks, and determine whether the number of cycles exceeds the number of cycles of the bench test equivalent to 6000km of bad road. If it exceeds, it means that the lateral stabilizer bar sample can meet the fatigue design target of the lateral stabilizer bar assembly;

[0036] S4.2, Sinusoidal load fatigue simulation analysis of lateral stabilizer bar;

[0037] The stress field and the sinusoidal load are superimposed by Fesafe software, and the fatigue life of the lateral stabilizer bar is calculated in combination with the material SN curve; static analysis is performed in the Abaqus calculation model, and Fesafe adopts the Brown-Miller criterion, a multi-axial fatigue life estimation model, and the Morrow mean stress correction, and sets its surface finish to;

[0038] The Brown-Miller criterion formula is:

[0039]

[0040] The Morrow mean stress correction formula is:

[0041]

[0042] in, is the maximum shear strain range; is the normal strain amplitude on the maximum shear strain surface; is the normal average stress on the critical plane; and are fatigue strength coefficient and fatigue ductility coefficient respectively; E is elastic modulus, N f is fatigue life; b and c are fatigue strength index and fatigue ductility index respectively; is the mean stress, is the total strain.

[0043] On the basis of the above scheme, further, the specific operation of step S5 is as follows:

[0044] Through the whole vehicle road sampling test, the random load spectrum of the road test is extracted to replace the sinusoidal load as the input condition of CAE simulation, and the actual working conditions of the prototype vehicle on different road surfaces in the test field are reproduced; within a test section cycle, the strain signal of the measuring point of the lateral stabilizer bar is filtered and denoised, and the singular value is removed. The vertical load and lateral load time history of the strain benchmark, that is, the road load spectrum, is used as the input condition to calculate the fatigue life of the lateral stabilizer bar assembly.

[0045] Compared with the prior art, the beneficial technical effects of the present invention are:

[0046] (1) Under the vertical load condition, the finite element model and simplified mechanical model of the lateral stabilizer bar were established respectively. The accuracy of the stress calculation of the finite element model of the lateral stabilizer bar was verified by mechanical theory calculation, and the finite element calculation accuracy of the roll stiffness of the lateral stabilizer bar was verified by stiffness bench test. Through comparative analysis, it is found that it is effective and feasible to use the finite element method to establish a static numerical model of the lateral stabilizer bar to predict its dangerous points, stress distribution and displacement distribution.

[0047] (2) The road load spectrum is combined with the bench fatigue test and virtual simulation technology to study the fatigue life of components. The bench test life and the simulated life can verify the authenticity of each other, and an integrated fatigue solution with both analysis and testing is established. This solution can be extended to other component systems, thereby shortening the development cycle of new products. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the finite element model of the lateral stabilizer bar;

[0049] Figure 2 is the maximum Mises stress at sections A and B;

[0050] Figure 2 a is the maximum Mises stress at section A;

[0051] Figure 2 b is the maximum Mises stress at section B;

[0052] Figure 3 is the mechanical model of the lateral stabilizer bar;

[0053] Figure 4 is the maximum Mises stress under the combined load condition;

[0054] Figure 5 It is a schematic diagram of vertical displacement of the loading point under vertical load action;

[0055] Figure 6 It is the roll stiffness test of the lateral stabilizer bar;

[0056] Figure 7 is the roll stiffness fitting curve;

[0057] Figure 8 Loading the stabilizer bar bench fatigue test for combined loads;

[0058] Fig. 9 This is the fracture position diagram of the fatigue bench test of the lateral stabilizer bar assembly;

[0059] Fig.10 Fatigue analysis life diagram of the lateral stabilizer bar loaded with a sinusoidal load history;

[0060] Fig.11 The time history of lateral and vertical loads of the stabilizer bar for a test section cycle;

[0061] Fig.12 is the fatigue load history coefficient. DETAILED DESCRIPTION

[0062] The principles of the present invention may be further understood by referring to the following detailed description and the embodiments shown in the accompanying drawings. However, it should be understood that although specific features are shown and described below with reference to the detailed embodiments, the present invention is not limited to the embodiments described below.

[0063] A method for studying the static and fatigue properties of a lateral stabilizer bar comprises the following steps:

[0064] Step S1, establishing a finite element model of a lateral stabilizer bar;

[0065] The stabilizer bar assembly is placed horizontally at the bottom of the vehicle and consists of a stabilizer bar body, a thrust rod, a rubber bushing and a clamp. The middle of the bar body is connected to the frame through a rubber bushing and a clamp, and the end of the thrust rod is connected to the suspension guide arm. The materials of the stabilizer bar body, the lower thrust rod and the clamp are 35CrMo, 40Cr and QSTE340, respectively. The main material parameters are shown in Table 1. The Mooney-Rivlin model is used to simulate the rubber bushing. The Shore hardness of the rubber is 60, and the positive constants and of the material are 0.722 and 0.014, respectively.

[0066] Table 1 Material parameters

[0067]

[0068] The stabilizer bar CAD model created in Catia is imported into the pre-processing software HyperMesh for geometric cleaning, meshing, unit quality inspection and assembly. The finite element model of the stabilizer bar assembly is obtained as follows: Figure 1 As shown. The finite element model is divided by tetrahedral mesh, which consists of 50881 units and 15753 nodes. In order to correctly simulate the connection relationship between the various components, contacts are established between the stabilizer bar body and the rubber bushing, and between the rubber bushing and the clamp. Tie binding constraints are used to simulate the welding between the stabilizer bar body and the thrust rod, without considering relative sliding. In order to simulate the complex constraints and stress transfer near the bolts, the bolt connection is simulated by combining beam elements and MPC constraints.

[0069] Step S2, performing static strength analysis of the lateral stabilizer bar;

[0070] Step S2.1: Static strength finite element analysis under vertical load

[0071] The load magnitude of the lateral stabilizer bar static analysis is obtained by sampling the maximum strain of the stabilizer bar through road durability test, and the maximum strain of the stabilizer bar is obtained by bench test calibration when a vertical load of ±25KN is applied to the stabilizer bar on one side. The y-direction freedom of movement at the 8 bolt holes connecting the lateral stabilizer bar body to the vehicle body and the 6 degrees of freedom of the mounting hole at one end of the thrust bar are constrained, and a concentrated force of 25KN is applied to the loading end of the thrust bar to complete the definition of the boundary conditions of the stabilizer bar assembly.

[0072] The finite element model was solved using the Abaqus standard solver, and the calculation results were post-processed using META. Figure 2 As shown in the figure, under the vertical load condition, the maximum MISES stress of the stabilizer bar is 386.2MPa, located at the welding point between the thrust rod and the stabilizer bar body, and the maximum Mises stress of the clamp is 67.5MPa. According to the strength parameters of different materials, all stabilizer bar components meet the strength conditions. In order to verify the accuracy of the finite element model of the lateral stabilizer bar using mechanical theory, the corresponding Figure 3 The maximum Mises stress at sections A and B are at node numbers 698 and 4838, and the stress magnitudes are 386.2 MPa and 323.8 MPa, respectively.

[0073] Step S2.2: Theoretical calculation of static strength under vertical load

[0074] According to the actual bench test loading method of the stabilizer bar, the mechanical model is simplified and established as follows Figure 3 As shown, the dimensions marked in the figure are H =950mm, l =600mm, b =70mm, k =90°. According to the beam theory of material mechanics, the Mises stress at A and B is theoretically calculated.

[14] , corresponding to the Mises stresses of nodes 698 and 4838 in the finite element calculation model respectively.

[0075] The cross section at A is a rectangular section with a size of 18mm×120mm. The thrust rod OA is mainly subjected to bending load, and its maximum bending moment is Fl , calculate the maximum normal stress in section A for:

[0076]

[0077] In the formula ，M A，max is the maximum bending moment of section A; is the moment of inertia of the rectangular section A about the neutral axis; F is the vertical load; is the width of the rectangular section at A; is the height of the rectangular section at A; is the farthest distance from the neutral plane; size is the height half.

[0078] Ignore the shear stress caused by shear force, that is . Applying the fourth strength theory to calculate, the maximum Mises stress of section A is obtained as:

[0079]

[0080] The cross section at point B is a circular ring with an outer diameter of D=80mm and an inner diameter of d=55mm. The AB section of the rod is subjected to a combined bending and torsion load, and its maximum bending moment is Fb , the torque is Fl , the maximum normal stress at section B is calculated as:

[0081]

[0082] The maximum shear stress in section B is:

[0083]

[0084] In the formula, is the bending section coefficient of the circular ring section, is the maximum bending moment of section B; is the torsional section coefficient of the ring section, is the torque of section B.

[0085] Ignore the shear stress caused by shear force, that is , the maximum Mises stress of section B is calculated by applying the fourth strength theory:

[0086]

[0087] The finite element calculation results and mechanical theory calculation results at sections A and B are compared. As shown in Table 2, the stress results of the two are relatively close, which verifies the correctness of the finite element model. The mechanical theory calculation simplifies the lateral stabilizer bar into a rigid frame and uses the Euler beam theory to calculate the stress results. The error is larger than the result obtained by the finite element method. The finite element model considers the influencing factors more comprehensively, and the main errors come from discrete errors and numerical errors.

[0088] Table 2 Comparison of cross-section Mises stress calculation results

[0089]

[0090] Step S2.3: Static strength finite element analysis of the lateral stabilizer bar under combined loads

[0091] During service, the lateral stabilizer bar is not only subjected to vertical loads, but also to lateral forces. The maximum lateral force actually measured on the road is 5kN. Generally speaking, there is a phase difference between the vertical load and the lateral load, and they do not reach the maximum value at the same time. For the convenience of processing, the present invention assumes that the loads in the two directions are in phase, that is, the maximum vertical load of 25kN and the maximum lateral load of 5kN act on the finite element model of the lateral stabilizer bar at the same time. This treatment is conservative. Under the combined load, the stress distribution of the lateral stabilizer bar is as follows: Figure 4 As shown in the figure, the maximum Mises stress is 494.9MPa, which occurs at the end of the thrust rod near the rod body on the loading side. By comparing the maximum stress of the stabilizer bar under the vertical load condition, it can be seen that the lateral force has a greater impact on the stress of the stabilizer bar, so in order to be closer to the actual working condition, it is necessary to consider the influence of both vertical load and lateral load.

[0092] Step S3, calculating the roll stiffness of the lateral stabilizer bar;

[0093] The lateral stabilizer bar is an important component for safely achieving the body roll condition, which is directly related to the safety of the driver. The lateral stabilizer bar can safely achieve the roll in the roll condition, which is an issue that needs to be considered in terms of stiffness. Figure 3 As shown, when the vehicle is rolling, the stabilizer bar body AC generates torque T=Fl , whose roll stiffness is defined as , is the rotation angle of section A.

[0094] S3.1. Rolling stiffness finite element calculation results

[0095] The lateral stabilizer bar is subjected to a vertical load of 25 kN When the vertical displacement of the loading point is 45.28 in post-processing mm ,like Figure 5 As shown,

[0096] The roll stiffness C1 of the finite element model can be calculated.

[0097]

[0098] Where w´ is the displacement of the position where the vertical load is applied in the finite element model.

[0099] S3.2. Lateral stabilizer bar roll stiffness bench test

[0100] The rigidity bench test is clamped according to the actual vehicle state. The clamping method is to fix one end of the thrust rod joint and rigidly connect the other end to the actuator according to the actual vehicle connection method. The actual fixing and loading diagram is as follows: Figure 6 shown.

[0101] Record the applied torque and the sample roll angle, and use the least squares method to fit the roll stiffness curve of the five sets of measurement data. Figure 7 As shown, the torque and roll angle are linearly related. Fitting, goodness of fit determination coefficient R 2 =0.999, the fitting effect is good, and the fitted test stiffness is 3359.7 N·m / °. By comparison, it can be seen that the finite element calculation results are within the reasonable error range, which verifies the accuracy of the finite element model. The main reason for the error is the numerical error of the finite element model.

[0102] Step S4, performing fatigue test and simulation analysis of the lateral stabilizer bar;

[0103] The lateral stabilizer bar is an important structural component in the automobile suspension. When it is fatigue fractured, it will seriously endanger the safety of vehicle driving. This paper combines CAE virtual fatigue analysis technology with component bench durability test technology to study the fatigue durability performance of the lateral stabilizer bar.

[0104] Step S4.1: Lateral stabilizer bar fatigue bench test

[0105] If the lateral stabilizer bar of the prototype vehicle in the present invention can meet the fatigue design target, it must meet the 6000km bad road test consisting of a mixed section of the test track, which consists of 1312 circles of stone road and comprehensive road. The stone road signal and the comprehensive road signal of the prototype vehicle are connected as a whole signal, and the rain flow count is performed on the strain signal of the lateral stabilizer bar to obtain a rain flow matrix within a test cycle, and then the rain flow matrix is ​​extrapolated and corrected to obtain the corrected rain flow matrix of 6000km bad road and serve as the target rain flow matrix. Through the material SN curve and the equal life conversion fatigue theory, the target rain flow matrix is ​​converted into a single-stage fixed amplitude, sinusoidal fixed frequency loaded signal required for the lateral stabilizer bench test. By writing a program, the amplitudes and frequencies of the 6000km bad road are converted into a single amplitude used for the bench test. After calculation, the 6000km bad road needs to be converted into 9433 bench test cycles.

[0106] In order to make the test closer to the actual working conditions, the fatigue bench test needs to consider the influence of lateral force. The maximum lateral force actually measured on the road is 5kN, which is a multi-axis fatigue problem and is non-proportional. In actual working conditions, there is a certain phase difference between the vertical load and the lateral load, but due to the limitations of the test conditions, this project ignores the phase effect and assumes that the loads in the two directions are in the same phase. The stabilizer bar is fixed in the form of a real vehicle support, with one end of the thrust rod joint fixed and the other end of the thrust rod joint loaded, such as Figure 8The applied load is a calibrated vertical load of 25 kN and a lateral load of 5 kN, which is a combined force of 25.5 kN, so that the load is carried out with a cylinder, and the cylinder is tilted 12.4° during loading, and the loading frequency is 0.3 Hz.

[0107] According to the test results, the three samples broke at 10855, 24363 and 30953 cycles respectively. The fracture locations are as follows: Fig. 9 As shown in the figure, all of them appear on the side of the thrust bar close to the stabilizer bar body, which is consistent with the maximum stress position in the static analysis under the combined load condition. The dispersion of the fatigue life of the lateral stabilizer bar assembly bench test is not large, and the number of cycles exceeds 9433 cycles of the bench test equivalent to 6000km bad road, which can meet the fatigue design target of the lateral stabilizer bar assembly.

[0108] Step S4.2: Sinusoidal load fatigue simulation analysis of the lateral stabilizer bar

[0109] Based on the results of the static analysis of the stabilizer bar considering the lateral force, the maximum stress of each component of the stabilizer bar is less than the yield strength of the material and is within the elastic deformation range, which is suitable for fatigue analysis using the SN nominal stress method. The stress field is superimposed on the sinusoidal load through the Fesafe software, and the fatigue life of the lateral stabilizer bar is calculated in combination with the material SN curve. Static analysis is performed in the Abaqus calculation model. Fesafe adopts the Brown-Miller criterion, a multi-axis fatigue life estimation model, and the Morrow mean stress correction, and sets its surface finish to. The fatigue analysis life cloud diagram of the lateral stabilizer bar assembly is as follows: Fig.10 shown.

[0110] The Brown-Miller criterion formula is:

[0111]

[0112] The Morrow mean stress correction formula is:

[0113]

[0114] in, is the maximum shear strain range; is the normal strain amplitude on the maximum shear strain surface; is the normal average stress on the critical plane; and are fatigue strength coefficient and fatigue ductility coefficient respectively; E is elastic modulus, N f is fatigue life; b and c are fatigue strength index and fatigue ductility index respectively; is the mean stress, is the total strain.

[0115] The minimum life is located on the thrust rod on the loading side, which is 10 4.129 times, that is, 13459 times. The fracture position of fatigue simulation is the same as that of bench fatigue test, and the predicted value of fatigue analysis is within 3 times of fatigue life test, indicating that this is a "good" prediction, and the fatigue life obtained by simulation can meet the fatigue design target of the stabilizer bar assembly.

[0116] Step S5: Perform road spectrum load fatigue analysis on the lateral stabilizer bar.

[0117] Through whole vehicle road sampling tests, the random load spectrum of the road test is extracted to replace the sinusoidal load as the input condition of the CAE simulation, and the actual working conditions of the prototype vehicle on different road surfaces in the test field are reproduced to improve the accuracy of the simulation analysis.

[0118] The test road selected was the mixed road section of the vehicle fatigue durability test at the Xiangyang test track. The specific road sections and mileage included 2.7km of stone road, 400m of washboard road, 200m of cobblestone road, 60m of twisted road, and 1.213km of connecting road, a total of 4.573km of bad road. The sampling frequency was 409.6HZ, and 6000km of bad road required 1312 cycles. In a test section cycle, the strain signal of the measuring point of the lateral stabilizer bar was filtered, denoised, and the singular value was removed. The vertical load and lateral load time history of the strain benchmark are shown in the following figure. Fig.11 The fatigue life of the stabilizer bar assembly is calculated by taking the road load spectrum as input.

[0119] In the Fesafe software environment, the target life value is set to 1312 cycles, and the FOS coefficient (fatigue load history coefficient) cloud diagram is calculated as follows: Fig.12 As shown, the minimum FOS coefficient is 1.094, that is, the fatigue life of the stabilizer bar is 1435 cycles, and the corresponding mixed bad road mileage on the test track is 6564km, which meets the 6000km bad road requirement of the project.

Claims

1. A method for studying the static and fatigue properties of a lateral stabilizer bar, characterized in that: The steps include: Step S1, establishing a finite element model of a lateral stabilizer bar; Step S2, performing static strength analysis of the lateral stabilizer bar; Step S3, calculating the roll stiffness of the lateral stabilizer bar; Step S4, performing fatigue test and simulation analysis of the lateral stabilizer bar; Step S5, perform road spectrum load fatigue analysis of the lateral stabilizer bar; The specific operation of step S3 is as follows: S3.

1. Perform finite element calculation of roll stiffness The formula for roll stiffness is as follows, ; in, T Generates torque for the stabilizer bar shaft, T=Fl , is the rotation angle of the cross section where the thrust rod and the stabilizer rod are welded; l To simplify the length of the thrust rod in the mechanical model, F is the vertical load, and w´ is the displacement of the position where the vertical load is applied in the finite element model; S3.

2. Perform lateral stabilizer bar roll stiffness bench test The stiffness bench test is clamped according to the actual vehicle state. The clamping method is to fix one end of the thrust rod joint and rigidly connect the other end to the actuator according to the actual vehicle connection form; record the applied torque and the size of the sample roll angle, and use the least squares method to fit the roll stiffness curve to the measured data; based on the fitting effect, verify the accuracy of the finite element model; The specific operation of step S4 is as follows: S4.

1. Conduct fatigue bench test on lateral stabilizer bar; Conduct a fatigue bench test on the lateral stabilizer bar of the sample under the combined load to obtain the number of cycles when the sample breaks, and determine whether the number of cycles exceeds the number of cycles of the bench test equivalent to 6000km of bad road. If it exceeds, it means that the lateral stabilizer bar sample can meet the fatigue design target of the lateral stabilizer bar assembly; S4.2, Sinusoidal load fatigue simulation analysis of lateral stabilizer bar; The stress field and the sinusoidal load are superimposed by Fesafe software, and the fatigue life of the lateral stabilizer bar is calculated in combination with the material SN curve; static analysis is performed in the Abaqus calculation model, and Fesafe adopts the Brown-Miller criterion, a multi-axial fatigue life estimation model, and the Morrow mean stress correction, and sets its surface finish to; The Brown-Miller criterion formula is: ； The Morrow mean stress correction formula is: ； in, is the maximum shear strain range; is the normal strain amplitude on the maximum shear strain surface; is the normal average stress on the critical plane; and are fatigue strength coefficient and fatigue ductility coefficient respectively; E is elastic modulus, N f is fatigue life; b and c are fatigue strength index and fatigue ductility index respectively; is the mean stress, is the total strain.

2. The method for studying the static and fatigue properties of a stabilizer bar according to claim 1, characterized in that: The specific operation of step S1 is as follows: The stabilizer bar CAD model established in Catia is imported into the pre-processing software HyperMesh for geometric cleaning, meshing, unit quality inspection and assembly to obtain a stabilizer bar assembly finite element model. The stabilizer bar consists of a stabilizer bar body, a thrust rod, a rubber bushing and a clamp. The Mooney-Rivlin model is used to simulate the rubber bushing. The finite element model is divided by tetrahedral mesh, which consists of 50881 units and 15753 nodes; Contact is established between the stabilizer bar body and the rubber bushing, and between the rubber bushing and the clamp. Tie binding constraints are used to simulate welding between the stabilizer bar body and the thrust rod, without considering relative sliding. The bolt connection is simulated by combining beam elements and MPC constraints.

3. The method for studying the static and fatigue properties of a stabilizer bar according to claim 1, characterized in that: The specific operation of step S2 is as follows: S2.

1. Conduct finite element analysis of static strength under vertical load; S2.

2. Perform theoretical calculation of static strength under vertical load; S2.

3. Perform finite element analysis of the static strength of the lateral stabilizer bar under combined loads.

4. The method for studying the static and fatigue properties of a stabilizer bar according to claim 3, characterized in that: The specific operation of step S2.1 is as follows: The load size of the lateral stabilizer bar static analysis is obtained by sampling the road durability test to obtain the maximum strain amplitude of the stabilizer bar, and the bench test calibration is used to obtain the maximum amplitude of the corresponding strain of the stabilizer bar when a vertical load of ±25KN is applied to the stabilizer bar on one side; the y-direction movement freedom at the 8 bolt holes connecting the lateral stabilizer bar body and the vehicle body and the 6 degrees of freedom of the mounting hole at one end of the thrust bar are constrained, and a concentrated force of 25KN is applied to the loading end of the thrust bar to complete the definition of the boundary conditions of the stabilizer bar assembly; the finite element model is solved using the Abaqus standard solver, and the calculation results are post-processed using META to obtain the maximum Mises stress at each position of the stabilizer bar.

5. The method for studying the static and fatigue properties of a stabilizer bar according to claim 3, characterized in that: The specific operation of step S2.2 is as follows: S2.

21. Select the two sections A and B in the finite element model of the lateral stabilizer bar and extract the maximum Mises stress at the two sections A and B; S2.

22. According to the actual bench test loading method of the stabilizer bar, simplify and establish the mechanical model, and perform theoretical calculations on the Mises stress at points A and B based on the beam theory of material mechanics; S2.

23. Compare the finite element calculation results and the mechanical theory calculation results at sections A and B. If the stress results of the two are close, the correctness of the finite element model is verified.

6. The method for studying the static and fatigue properties of a stabilizer bar according to claim 3, characterized in that: The specific operation of step S2.3 is as follows: The maximum vertical load of 25kN and the maximum lateral load of 5kN are applied to the finite element model of the lateral stabilizer bar at the same time, and the stress distribution of the lateral stabilizer bar under the combined load is obtained. By comparing it with the maximum stress of the stabilizer bar under the vertical load condition, the influence of the vertical load and the lateral load on the stress condition of the stabilizer bar is determined.

7. The method for studying the static and fatigue properties of a stabilizer bar according to claim 1, characterized in that: The specific operation of step S5 is as follows: Through the whole vehicle road sampling test, the random load spectrum of the road test is extracted to replace the sine load as the input condition of the CAE simulation, and the actual working conditions of the prototype vehicle on different road surfaces in the test field are reproduced; In a test section cycle, after filtering and denoising the strain signals of the measuring points of the lateral stabilizer bar and removing singular values, the vertical load and lateral load time history of the strain benchmark, i.e., the road load spectrum, is used as the input condition to calculate the fatigue life of the lateral stabilizer bar assembly.

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