Linearized tire model building method

Abstract

The present invention relates to the technical field of vehicle road noise simulation. Disclosed is a linearized tire model building method. The method comprises: building a two-dimensional tire finite element model on the basis of a material distribution diagram, gridding parts of a tire, and defining different material parameters; performing inflation, loading and rolling simulation; performing modal simulation; and then using special software to generate a linearized tire model. During finite element model building, a cavity characteristic is added for the linearized tire model, and during simulation, tire cavity air property parameters are given; in order to consider the damping characteristic of the tire, a rubber component in the finite element model is represented by a hyperelastic Yeoh model and a viscoelastic model represented by a Prony series, and a cord is described by a linear elastic constitutive model; and the finite element model is a model with a speed, and simulation at any rolling speed can be performed, so that the linearized tire model comprises a speed characteristic, making linearized tire model building more accurate.

Description

A linear tire modeling method Technical Field

[0001] The present invention relates to the technical field of vehicle road noise simulation, and in particular to a linear tire modeling method. Background Art

[0002] When a vehicle travels on a non-smooth road, road features interact with the tires, generating excitations. This excitation is then transmitted through the tires to the vehicle structure, causing structural vibrations and further compressing the acoustic cavity, generating noise. As the only way to transmit road excitation to the wheel center, the tire's vibration isolation performance significantly impacts the overall vehicle's NVH performance. In simulation, considering the impact of road feature excitation on the vehicle's NVH performance requires accurate tire modeling to fully reflect the changes in road excitation after it passes through the tire.

[0003] Cavity noise in vehicle road noise simulation significantly affects driving comfort, but existing methods cannot characterize the impact of cavity noise because tires do not have cavities.

[0004] In the whole vehicle road noise simulation, the vehicle should be in a driving state, but the existing technology is based on static loading conditions, which is inconsistent with the actual working conditions, affecting its accuracy in the whole vehicle road noise simulation.

[0005] In the whole vehicle road noise simulation, the rubber and cord materials are not properly selected, and the damping characteristics of the tire cannot be represented.

[0006] In response to the above problems, an improved linearized tire modeling method is now designed. Summary of the Invention

[0007] The object of the present invention is to provide a linear tire modeling method to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A linear tire modeling method includes the following steps:

[0010] Step 1: Finite element model building

[0011] After the tire structure design is completed, a two-dimensional tire finite element model is established based on the material distribution map. Based on the semi-component design parameters, the meshes of each part of the tire are divided in sequence to facilitate the definition of different material parameters. The mesh part at the center of the tire is defined as the tire cavity, and the air property parameters of the tire cavity are assigned during the simulation process.

[0012] In order to consider the damping characteristics of the tire, the rubber components in the finite element model are represented by a viscoelastic model composed of a hyperelastic Yeoh model and a Prony series, and the cord is described by a linear elastic constitutive model.

[0013] Step 2: Inflation, loading, and rolling simulation

[0014] To make the linearized tire model more accurate, inflation and loading simulations are required. Using dedicated simulation software, the two-dimensional tire model is first assembled with the selected rim for simulation. Then, the same distributed pressure as in the operating conditions is applied to the inner surface of the tire. After the inflation simulation is completed, the two-dimensional tire model is rotated around the axle to generate a three-dimensional tire finite element model. A three-dimensional inflation simulation is then performed, and then a loading simulation is performed based on the actual operating load.

[0015] After static loading is completed, the next step is to perform rolling simulation. Based on the driving speed required in the vehicle test, the rolling simulation of the tire is performed under the working condition. The key point of rolling simulation is to determine the free rolling angle of the tire when the vehicle is driving at a constant speed. The method adopted by the present invention is to determine the free rolling angular velocity through braking-driving working condition simulation using interpolation method.

[0016] Step 3: Modal Simulation

[0017] After the tire completes free-rolling simulation, modal simulation is performed. The tire model at this point specifies the air pressure, load, and rolling speed, and takes into account cavity characteristics. The modal solution is the Lanczos method within the vector iteration method. Since vehicle road noise simulation generally requires component modal frequencies to be above 250 Hz, all modes within the 1-300 Hz range are extracted during the modal solution. This frequency range covers the range of major modes, such as the tire's low-frequency structural modes and cavity modes.

[0018] Step 4: Linear model building, data mapping, and verification

[0019] After completing the modal simulation, a linearized tire model can be generated using dedicated pre-processing software or by programming. As shown in Figure 5, a hybrid component modal synthesis method is used to extract and convert the modal simulation results. Data mapping is then performed based on the generated linearized tire model. The mass matrix, stiffness matrix, and damping matrix are assembled according to the DMIG matrix requirements to form a .dat model file that can be used for full-vehicle road noise simulation.

[0020] As a further solution of the present invention: in step 2, the pressure applied to the inner surface of the tire is: 250 kPa.

[0021] As a further solution of the present invention: in step 2, the speed of the tire rolling simulation is: 40 km / h.

[0022] As a further solution of the present invention: in step 2, the speed of the tire rolling simulation is: 60 km / h.

[0023] As a further solution of the present invention, the damping characteristics of the linearized tire model are characterized by structural damping, and the structural damping formula is shown as follows:

[0024] Formula (1)

[0025]

[0026] According to the system dynamics equation, combined with formula (1), the modal damping ratio can be derived:

[0027] Formula (2)

[0028]

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] When building the finite element model, cavity characteristics are added to the linearized tire model, and air property parameters are assigned to the tire cavity during the simulation process, making the linearized tire model more accurate.

[0031] In order to consider the damping characteristics of the tire, the rubber components in the finite element model are represented by a viscoelastic model composed of a hyperelastic Yeoh model + a Prony series, and the cord is described by a linear elastic constitutive model, making the linear tire model more accurate.

[0032] The finite element model is a model with speed, which can be simulated at any rolling speed, so that the linearized tire model includes speed characteristics, making the linearized tire model more accurate.

[0033] The hybrid component modal synthesis method used in the linear model building process can accurately characterize its dynamic characteristics, make its dynamic characteristics consistent with the finite element model, and make the linear tire modeling more accurate.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a flow chart of the modeling process of the present invention.

[0036] FIG2 is a two-dimensional tire model of the present invention.

[0037] FIG3 is a curve of the rolling angular velocity of the tire around the axis under the braking-driving condition in the present invention.

[0038] FIG4 is a torque curve about the wheel axle when the tire rotates from a static loading state to a free rolling angular velocity in the present invention.

[0039] FIG5 shows the linearized tire model and calibration in the present invention.

[0040] FIG6 is a comparison of the frequency response functions of the linearized tire model and the finite element model in the present invention.

[0041] DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Referring to Figures 1 to 6, a linear tire modeling method includes the following steps:

[0044] Step 1: Finite element model building

[0045] After the tire structure design is completed, a two-dimensional tire finite element model is established based on the material distribution map. Based on the semi-component design parameters, the meshes of each part of the tire are divided in sequence to facilitate the definition of different material parameters. The mesh part at the center of the tire in Figure 2 is defined as the tire cavity, and the air property parameters are assigned to the tire cavity during the simulation process.

[0046] In order to consider the damping characteristics of the tire, the rubber components in the finite element model are represented by a viscoelastic model composed of a hyperelastic Yeoh model and a Prony series, and the cord is described by a linear elastic constitutive model.

[0047] Step 2: Inflation, loading, and rolling simulation

[0048] To make the linearized tire model more accurate, inflation and loading simulations are required. Using dedicated simulation software, the two-dimensional tire model is first assembled with the selected rim for simulation. Then, the same distributed pressure as in the operating conditions is applied to the inner surface of the tire. After the inflation simulation is completed, the two-dimensional tire model is rotated around the axle to generate a three-dimensional tire finite element model. A three-dimensional inflation simulation is then performed, and then a loading simulation is performed based on the actual operating load.

[0049] After static loading is completed, the next step is to perform rolling simulation. Based on the driving speed required in the vehicle test, the rolling simulation of the tire is performed under the working condition. The key point of rolling simulation is to determine the free rolling angle of the tire when the vehicle is driving at a constant speed. The method adopted by the present invention is to determine the free rolling angular velocity through braking-driving working condition simulation using interpolation method.

[0050] The rolling angular velocity curve of the tire around the axis under the braking-driving condition is shown in Figure 3. Interpolation is performed based on the scattered points of the curve to calculate the tire rolling angular velocity when the torque is 0 when rotating around the axis, which is the required free rolling angular velocity. The torque curve of the tire around the wheel axis when it rotates from the static loading state to the free rolling angular velocity is shown in Figure 4. It can be seen from the curve that when the simulation time is close to 1, the torque around the wheel axis is basically close to 0, that is, the free rolling state is reached. If the torque is not close to 0 at the end of the simulation step, it means that the tire has not reached the free rolling state.

[0051] Step 3: Modal Simulation

[0052] After the tire completes free-rolling simulation, modal simulation is performed. At this time, the tire model specifies the air pressure, load, and rolling speed, and takes into account the cavity characteristics. Modal solution methods include direct method and vector iteration method. Considering economy and simulation accuracy, the Lanczos method of vector iteration method is determined to be used for solution. Since vehicle road noise simulation generally requires the component modal frequency to reach above 250Hz, all modes in the range of 1 to 300Hz are extracted during modal solution. This frequency range covers the range of major modes such as the tire's low-frequency structural mode and cavity mode.

[0053] Step 4: Linear model building, data mapping, and verification

[0054] After completing the modal simulation, a linearized tire model can be generated using dedicated pre-processing software or by programming. As shown in Figure 5, a hybrid component modal synthesis method is used to extract and convert the modal simulation results. Data mapping is then performed based on the generated linearized tire model. The mass matrix, stiffness matrix, and damping matrix are assembled according to the DMIG matrix requirements to form a .dat model file that can be used for full-vehicle road noise simulation.

[0055] The most important aspect of a linearized tire model is its ability to characterize dynamic characteristics. The most commonly used approach is to examine the variable as a frequency response function. Excitations of identical magnitude are applied to the road reference points of the linearized tire model and the finite element tire, as shown in Figure 5. The response at the wheel center is extracted, as shown in Figure 6. Comparing the curves in Figure 6 shows that the frequency response function curve of the linearized tire model almost coincides with that of the finite element model, demonstrating that the linearized tire modeling method of the present invention is extremely accurate.

[0056] During use, tires play an important role in reducing vibration and noise. A large part of tires is rubber, a viscoelastic energy-absorbing material. The viscoelastic constitutive model used in the present invention is also used to provide damping parameters for the linearized model. The damping characteristics of the linearized tire model of the present invention are characterized by structural damping. The structural damping formula is shown as follows:

[0057] Formula (1)

[0058]

[0059] According to the system dynamics equation, combined with formula (1), the modal damping ratio can be derived:

[0060] Formula (2)

[0061]

[0062] According to formula (2), the modal damping calculation results of a linearized tire model are shown in Table 1, which can be assembled into the damping matrix of the linearized tire model.

[0063] Table 1: An example of modal damping calculation

[0064] Order Real part Imaginary part Frequency / Hzηζ1-3.8272126.9120.1980.06030.48%2-5.5526158.1225.1650.07020.56%3-15.614232.4736.9990.13431.07%4-14.386299.6247.68 60.09600.76%5-32.454577.5891.9240.11240.89%6-36.344585.8893.2450.12410.99%7-39.038747.34118.940.10450.83%8-40.556804.96128.11 0.10080.80%9-37.802805.51128.20.09390.75%10-57.263877.48139.660.13051.04%11-38.149914.78145.590.08340.66%12-58.077955.01151.9 90.12160.97%13-57.4941034.5164.640.11120.88%14-59.4611044.5166.240.11390.90%15-91.991067169.820.17241.37%16-43.5561094.7174.2 20.07960.63%17-73.7871171.2186.410.12601.00%18-45.3251190.1189.420.07620.61%19-60.3071191.1189.570.10130.80%20-57.4141244197. 980.09230.73%21-45.2591278.4203.460.07080.56%22-76.5751326.1211.060.11550.92%23-86.1291355.8215.780.12711.01%24-52.6571371218 .210.07680.61%25-145.181439.7229.140.20171.60%26-52.0811466.4233.380.07100.56%27-85.9491474.1234.620.11660.93%28-93.1021490.1 237.160.12500.99%29-60.4391566.4249.30.07720.61%30-94.921609.5256.170.11800.94%31-99.2641617.4257.410.12280.97%32-62.5941659.4264.10.07540.60%33-104.921740.3276.980.12060.96%34-106.951751.1278.690.12220.97%35-72.3281759.7280.070.08220.65%36-79.5321855.9295.370.08570.68%37-116.521871.6297.880.12450.99%.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

Claims

1. A linear tire modeling method, characterized in that: The following steps are involved: Step 1: Finite element model building After the tire structure design is completed, a two-dimensional tire finite element model is established according to the material distribution map. According to the semi-component design parameters, the meshes of each part of the tire are divided in turn to facilitate the definition of different material parameters. The mesh part at the center of the tire is defined as the tire cavity, and the tire cavity is given air property parameters during the simulation process; In order to consider the damping characteristics of the tire, the rubber components in the finite element model are represented by the viscoelastic model represented by the hyperelastic Yeoh model + Prony series, and the cord is described by the linear elastic constitutive model; Step 2: Inflation, loading, and rolling simulation In order to make the linearized tire model more accurate, it is necessary to first perform inflation and loading simulations. Using dedicated simulation software, the 2D tire model is first assembled with the selected rim for simulation, and then the same distributed pressure as the operating condition is applied to the inner surface of the tire. After the inflation simulation is completed, the 2D tire model is rotated around the axle to generate a 3D tire finite element model, and a 3D inflation simulation is performed, and then a loading simulation is performed according to the actual operating load. After the static loading is completed, the next step is to perform rolling simulation. According to the driving speed required in the vehicle test, the rolling simulation of the tire under the working condition is performed. The key point of the rolling simulation is to determine the free rolling angle of the tire when the vehicle is driving at a constant speed. The method adopted by the present invention is to determine the free rolling angular velocity by interpolation method through braking-driving working condition simulation; Step 3: Modal Simulation After the tire completes the free rolling simulation, the modal simulation is performed. At this time, the tire model is a model with specified air pressure, load, rolling speed, and cavity characteristics. The modal solution method adopts the Lanczos method in the vector iteration method. Since the whole vehicle road noise simulation generally requires the modal frequency of the component to reach above 250Hz, all modes in the range of 1 to 300Hz are extracted during the modal solution. This frequency range covers the range of the main modes such as the tire low-frequency structural mode and cavity mode. Step 4: Linear model building, data mapping, and verification After completing the modal simulation, a linearized tire model can be generated by using dedicated pre-processing software or writing a program. The modal simulation results are extracted and converted using a mixed component modal synthesis method. Data mapping is performed based on the generated linearized tire model. The mass matrix, stiffness matrix, and damping matrix are assembled according to the DMIG matrix requirements to form a .dat model file that can be used for the vehicle road noise simulation.

2. A linear tire modeling method according to claim 1, characterized in that: In step 2, the pressure applied to the inner surface of the tire is: 250 kPa.

3. A linear tire modeling method according to claim 1, characterized in that: In step 2, the speed of tire rolling simulation is: 40km / h.

4. A linear tire modeling method according to claim 1, characterized in that: In step 2, the speed of tire rolling simulation is: 60km / h.

5. A linear tire modeling method according to claim 1, characterized in that: The damping characteristics of the linearized tire model are characterized by structural damping. The structural damping formula is shown as follows: Formula (1) 6. According to the system dynamics equation, combined with formula (1), the modal damping ratio can be derived: Formula (2) 。

Images