A method for characterizing the vibration smoothness of rolling over obstacles of non-pneumatic tires

Abstract

The present invention discloses a method for characterizing the rolling obstacle-crossing vibration smoothness of a non-pneumatic tire, comprising the following steps: Step 1, establish an initial non-pneumatic tire model; Step 2, establish a flat-ground obstacle-crossing simulation analysis model of the non-pneumatic tire; Step 3, design an experimental scheme; Step 4, use a statistical analysis method to analyze the relationship between the standard deviation σ of the peak ground contact pressure and the root mean square (RMS) value of the vertical excitation force; Step 5, obtain a method for characterizing the smoothness of the non-pneumatic tire when crossing obstacles of different obstacle heights. Beneficial effects: The present invention can effectively avoid the blindness problem existing in the structural design of non-pneumatic tires for optimizing the vibration characteristics of non-pneumatic tires, thereby shortening the design cycle and improving efficiency. At the same time, it also plays a certain guiding role in the improvement of the vibration characteristics of non-pneumatic tires. GPP The present invention can effectively avoid the blindness problem existing in the structural design of non-pneumatic tires for optimizing the vibration characteristics of non-pneumatic tires, thereby shortening the design cycle and improving efficiency. At the same time, it also plays a certain guiding role in the improvement of the vibration characteristics of non-pneumatic tires.

Description

Technical Field

[0001] The invention relates to a method for characterizing smoothness, in particular to a method for characterizing the vibration smoothness of rolling over obstacles of a non-pneumatic tire, and belongs to the technical field of vehicle tires. Background Art

[0002] Tires are the only part of a vehicle that comes into contact with the road, and they play a vital role in the driving process. Although traditional pneumatic tires have the advantages of good adhesion, uniform ground pressure distribution, and good fuel economy, they are thinner on the sidewalls and have poor impact resistance, which can easily cause cuts, blowouts, and punctures, which become important factors threatening vehicle driving safety. About 46% of traffic accidents in my country are caused by tire failures, and blowouts account for as much as 70%. Compared with traditional pneumatic tires, non-pneumatic tires (NPT) rely on the spoke structure instead of the air pressure of pneumatic tires to play the role of load bearing, cushioning and vibration reduction, and providing force, thus avoiding the dangers of blowouts and air leaks.

[0003] The support body of the non-pneumatic tire supports the mass of the whole vehicle instead of the inflation pressure, and bears tensile and compressive loads during the driving process of the vehicle. However, compared with the better uniformity of mass distribution of traditional pneumatic tires, the discontinuous spoke support structure of the non-pneumatic tire leads to its non-uniform stiffness, resulting in fluctuations in ground pressure and ground area, thereby causing overall and local vibration effects of the non-pneumatic tire. The prominent vibration problem of non-pneumatic tires limits the increase in the speed of vehicles equipped with non-pneumatic tires and hinders the development of non-pneumatic tires. Therefore, how to reduce vibration has become one of the key issues in the development of non-pneumatic tires. The vibration source of non-pneumatic tires during rolling is the buckling and rebound phenomenon of the spokes under tension when entering and leaving the contact area. The discontinuous spokes serve as a transmission bridge between the road excitation force and the wheel rim vibration. The spokes have a great influence on the vibration of the non-pneumatic tire. Therefore, the vibration reduction design of the spokes is one of the keys to achieve vibration reduction of non-pneumatic tires.

[0004] At present, the research on non-pneumatic tires is mainly focused on the analysis of external characteristics such as static stiffness and ground contact characteristics, and there is a lack of relevant research on dynamic vibration characteristics. In addition, vibration research is mainly limited to exploring the influence of vibration by changing material and structural parameters, and there is a lack of analysis of innovative vibration reduction research methods. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to propose a method for characterizing the vibration smoothness of rolling obstacle crossing of a non-pneumatic tire in response to the needs of existing research on non-pneumatic tires. The present invention takes the evaluation method of the vibration smoothness of non-pneumatic tires as the goal, sets the obstacle crossing of non-pneumatic tires as the condition, and analyzes the relationship between the ground contact pressure characteristics and vertical vibration characteristics of non-pneumatic tires under the influence of different obstacle crossing speeds and obstacle heights. This can effectively avoid the blindness problem in the structural design of non-pneumatic tires in order to optimize the vibration characteristics of non-pneumatic tires, thereby shortening the design cycle and improving efficiency. At the same time, it also plays a certain guiding role in improving the vibration characteristics of non-pneumatic tires, thereby improving the riding safety of drivers.

[0006] Technical solution: A method for characterizing the vibration smoothness of rolling over obstacles of a non-pneumatic tire, comprising the following steps:

[0007] Step 1: Establish an initial non-pneumatic tire model, and establish a three-dimensional model of the tire according to the outer contour parameters of the non-pneumatic tire;

[0008] Step 2: Construct a tire obstacle crossing simulation analysis model to analyze the flat ground obstacle crossing behavior of non-pneumatic tires. The obstacle crossing process is divided into five states: tire obstacle crossing starts (a), contacts the obstacle (b), is completely on the obstacle (c), is about to leave the obstacle (d), and ends the obstacle crossing (e). The standard deviation σ of the tire ground contact pressure peak value in the five states is obtained. GPP ;

[0009] Step 3: Design a test plan. Take tire speed and obstacle height as variables to design a test plan. Take the root mean square (RMS) value of the vertical excitation force of the road contact force in the frequency domain as the target response value. Perform simulation analysis on the obstacle crossing process of non-pneumatic tires for different design experimental plans to obtain the target response value under each obstacle crossing condition.

[0010] Step 4: Analyze the standard deviation σ of the ground pressure peak using statistical analysis methods GPP , and the relationship between the RMS value of the vertical excitation force;

[0011] Step 5: Obtain a characterization method for the ride comfort of a non-pneumatic tire when crossing obstacles of different obstacle heights, based on the standard deviation of the peak ground contact pressure σ GPP The positive correlation with the root mean square RMS and the standard deviation of the ground pressure peak value obtained in the five states during the obstacle crossing process indicate that the obstacle crossing vibration intensity changes with the increase or decrease of the obstacle height. By analyzing the standard deviation of the ground pressure peak value σ GPP To judge the obstacle vibration smoothness of non-pneumatic tires.

[0012] The present invention aims at an evaluation method for the vibration smoothness of a non-pneumatic tire, sets obstacle crossing of a non-pneumatic tire as a condition, and analyzes the relationship between the ground contact pressure characteristics and vertical vibration characteristics of a non-pneumatic tire when crossing obstacles under the influence of different obstacle crossing speeds and obstacle heights. A method for characterizing the vibration smoothness of a non-pneumatic tire rolling over obstacles is proposed, which lays a theoretical foundation and methodological guidance for the research on vibration characteristics and structural optimization design expansion of non-pneumatic tires.

[0013] Preferably, in order to establish an accurate non-pneumatic tire model, the non-pneumatic tire structural parameters in step 1 include hub diameter, tire width, flexible ring thickness, tread thickness, spoke thickness, spoke curvature, and spoke quantity.

[0014] Preferably, in order to perform obstacle crossing vibration analysis on the established non-pneumatic tire at different speeds, the Abaqus / Explicit method is used in step 2 to constrain the vertical degree of freedom of the tire, apply a vertical load to the tire through the road, extract the road surface vertical excitation force in the time domain during the non-pneumatic tire obstacle crossing process at different speeds, perform Fourier transform on it to obtain the road surface vertical excitation force in the frequency domain, and use the road surface vertical excitation force RMS in the frequency domain to perform vibration smoothness analysis on the non-pneumatic tire rolling obstacle crossing, wherein the calculation formula of the road surface vertical excitation force RMS value is:

[0015]

[0016] Where N is the number of vertical excitation force sample points in the frequency domain, x i is the specific excitation force amplitude at the i-th sample point.

[0017] Preferably, in order to extract the vertical excitation force of the road surface in the time domain during the obstacle crossing of the non-pneumatic tire for vibration characteristic analysis, the five states in the step 2 are specifically: the obstacle crossing start state is that the rolling non-pneumatic tire is 1-2 meters away from the obstacle, the obstacle contact state is that the non-pneumatic tire tread is in contact with one side of the obstacle and the tread does not undergo any bending deformation at this time; the obstacle is completely on the obstacle state is that the width of the obstacle is completely covered by the non-pneumatic tire tread and the tread deformation is maximum at this time; the obstacle detachment state is that the non-pneumatic tire tread is detached from the obstacle and no bending deformation occurs at this time; the obstacle crossing end state is that the non-pneumatic tire is 2-3 meters away from the obstacle.

[0018] Preferably, in order to further perform obstacle vibration analysis on the established non-pneumatic tire at different speeds, the obstacle height during tire driving in step three ranges from 10mm to 30mm, and the driving speed ranges from 10km / s to 30km / s.

[0019] Preferably, in order to obtain the accurate RMS value of the vertical excitation force during the tire obstacle crossing and the ground pressure peak values ​​under five states, the statistical experimental design method in step 4 is a full factorial experimental design method, and numerical simulation is used to obtain the RMS value of the vertical excitation force during the tire obstacle crossing and the ground pressure peak values ​​under five states under different experimental design schemes.

[0020] Preferably, in order to analyze the influence of non-pneumatic tires at different obstacle crossing speeds and obstacle heights under the setting of non-pneumatic tire obstacle crossing driving conditions, the functional relationship in step 4 is to establish a changing relationship based on the root mean square RMS value of the vertical excitation force of the tire obstacle crossing vibration characteristics and the obstacle height and driving speed.

[0021] Preferably, in order to judge the obstacle vibration smoothness of the non-pneumatic tire by analyzing the standard deviation of the ground contact pressure peak value, the standard deviation σ of the ground contact pressure peak values ​​in the five states is taken GPP , using σ GPP The value represents the fluctuation of the tire ground pressure during the obstacle crossing process, and the standard deviation σ GPP The value is calculated as follows:

[0022]

[0023] In the formula, μ is the value x 1 …x N The average value, x i is the ground pressure peak value under five conditions, i=5.

[0024] σ for non-pneumatic tires GPP The value increases with the increase of obstacle height, which means that the increase of obstacle height increases the ground contact pressure fluctuation of the tire when crossing the obstacle and increases the instability of tire ground contact.

[0025] Standard deviation of peak ground pressure over obstacle σ GPP There is a positive correlation with RMS, so the standard deviation of the ground pressure peak value under five conditions is obtained during the obstacle crossing process. GPP It can be reasonably explained that the intensity of obstacle crossing vibration changes with the increase or decrease of obstacle height, and there is a positive correlation between the two. The obstacle crossing vibration smoothness of non-pneumatic tires can be judged by analyzing the standard deviation of the ground contact pressure peak value; and the standard deviation of the obstacle crossing ground contact pressure peak value σ GPP The positive correlation with RMS can be used to determine the smoothness of the vibration of a non-pneumatic tire over an obstacle.

[0026] Beneficial effects: The present invention can effectively avoid the blind problem in the non-pneumatic tire structure design in order to optimize the vibration characteristics of the non-pneumatic tire, thereby shortening the design cycle and improving efficiency. At the same time, it also plays a certain guiding role in improving the vibration characteristics of the non-pneumatic tire, thereby improving the riding safety of the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 It is a design flow chart of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of the non-pneumatic tire of the present invention;

[0030] Figure 3 This is a schematic diagram of the tire obstacle crossing simulation model;

[0031] Figure 4 is the obstacle type and parameters;

[0032] Figure 5 Comparison of vertical excitation forces in the time domain when a non-pneumatic tire passes over an obstacle at different speeds;

[0033] Figure 6 Comparison of vertical excitation forces in the time domain when a non-pneumatic tire passes over obstacles of different heights;

[0034] Figure 7 Comparison of vertical excitation force amplitudes of non-pneumatic tires crossing obstacles at different speeds;

[0035] Figure 8 Comparison of vertical excitation force amplitudes of non-pneumatic tires crossing obstacles of different heights;

[0036] Fig. 9 The variation law of the vertical vibration amplitude of non-pneumatic tire with speed and obstacle height;

[0037] Fig.10 It is the obstacle crossing process of non-pneumatic tires;

[0038] Fig.11 is the σ of a non-pneumatic tire crossing obstacles of different heights GPP ;

[0039] Fig.12 σ is the height of different obstacles when crossing the obstacle GPP Relationship with RMS;

[0040] Fig.13 When crossing an obstacle at a certain height, the speed of the obstacle is different. GPP Schematic diagram of the relationship with RMS;

[0041] Table 1 shows the RMS of different speeds and obstacle heights during the obstacle crossing process;

[0042] Table 2 shows the peak ground pressure and σ of the five steps at the same obstacle height and different obstacle crossing speeds. GPP ;

[0043] Table 3 shows the ground pressure peaks and σ of the five steps at the same obstacle crossing speed and different obstacle heights. GPP . DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0045] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] like Figure 1 As shown, a method for characterizing the vibration smoothness of rolling over obstacles of a non-pneumatic tire comprises the following steps:

[0048] Step 1: Establish an initial non-pneumatic tire model, and draw a three-dimensional model of the tire according to the outer contour parameters of the non-pneumatic tire; this embodiment takes a spoke-type non-pneumatic tire as an example, and its tire outer diameter is 593mm, the hub diameter is 410mm, the tire width is 195mm, the flexible ring thickness is 19.5mm, the tread thickness is 2.95mm, the spoke thickness is 4.2mm, the spoke curvature is 8mm, the number of spokes is 50 (25 pairs), the hub is made of aluminum alloy material, and the deformable spokes are made of polyurethane material. Establish the following in ABAQUS: Figure 2 The 3D model of the tire is shown.

[0049] Step 2: Construct a tire obstacle crossing simulation analysis model, such as Figure 3 As shown. Based on the above three-dimensional model of the tire, a tire obstacle crossing simulation model is constructed, and numerical simulation analysis is performed to obtain the vertical excitation force of the tire crossing the obstacle under the initial conditions;

[0050] Using the Abaqus / Explicit method, the vertical freedom of the tire is constrained, and a 3665N vertical load is applied to the tire through the road. The obstacle vibration analysis of the non-pneumatic tire at different speeds is performed. The shape of the road obstacle is rectangular. The width of the rectangle is kept unchanged, and the height of the obstacle is changed to form three different obstacles, such as Figure 4 As shown in the figure, the transition parts at both ends of the obstacle are processed into arcs, and the radius of the arc is 50% of the obstacle height. The vertical excitation force of the road surface in the time domain during the tire obstacle crossing process is extracted to analyze the vibration characteristics.

[0051] Step 3: Design the test plan, take the tire speed and obstacle height as variables, set the value range of the variables, and take the RMS value as the target response value; design the plan for the tire speed and obstacle height through the full factorial experimental design method, simulate and analyze the obstacle crossing process of the non-pneumatic tire for the models of different plans, and obtain the vertical excitation force of the tire at the tread under various obstacle crossing conditions;

[0052] Extract the vertical excitation force when the tire passes over obstacles of different heights without inflation, and analyze the influence of the height change of the obstacle on the vertical vibration of the tire, such as Figure 5 As shown. Figure 5 It can be seen that when the tire passes over three obstacles of different heights at the same speed, the local and overall fluctuations of the tire vertical excitation force become more intense as the obstacle height increases. The main reason is that when the tire is subjected to vertical load, the spatial position of the tire in the vertical direction is effectively restricted, making it fixed. When the obstacle height increases, the spoke will produce greater deformation in the vertical direction, resulting in an increase in the vertical force on the road surface and an increase in the fluctuation of the excitation force.

[0053] Step 4: Analyze the standard deviation σ of the ground pressure peak using statistical analysis methods GPP, and the relationship between the RMS value of the vertical excitation force;

[0054] The RMS value of the vertical excitation force is calculated according to the following method, and the influence of obstacle height and obstacle traversal speed on the vertical vibration is analyzed.

[0055] Generally speaking, the greater the deviation of the vertical excitation force of the rolling tire, the greater the impact change of the road on the tire, which in turn affects the vibration smoothness of the tire. When the tire passes over a 10mm obstacle, an obvious vertical excitation force fluctuation peak appears at the position directly above the obstacle. This is because compared with rolling on flat ground, the presence of the obstacle increases the vertical deformation of the non-pneumatic tire, thereby enhancing the force fluctuation. When the obstacle height increases from 10mm to 20mm, the fluctuation peak of the tire vertical excitation force gradually appears at both ends of the tire contact with the obstacle. This is because when the tire suddenly hits the obstacle from rolling on flat ground, the ground contact area decreases instantly and the vertical deformation increases sharply, which leads to a significant increase in the fluctuation of the tire vertical excitation force. The increase in the obstacle height can enhance this effect, so the fluctuation peak gradually increases from one to three. When the obstacle height is 30mm, the fluctuation peaks at both ends of the contact increase significantly and are significantly higher than the peak value directly above the obstacle. It can be seen that the increase in the obstacle height will enhance the impact force of the tire when crossing the obstacle and intensify the fluctuation change of the excitation force.

[0056] The vertical excitation force fluctuations of a non-pneumatic tire when crossing an obstacle at different speeds are shown in the figure below: Figure 6 As shown in the figure, it can be seen that with the increase of obstacle crossing speed, the time for the tire to hit and cross the obstacle is shortened. The increase of impact speed increases the impact force on the tire, which in turn leads to an increase in the fluctuation of the vertical excitation force. The higher the speed, the greater the peak value of the excitation force at both ends of the tire and the obstacle, and the greater the residual fluctuation after the tire crosses the obstacle. Therefore, although the obstacle height and obstacle crossing speed affect the vertical excitation force fluctuation in different ways, under the same load, increasing the tire speed and obstacle height will aggravate the vertical excitation force fluctuation of the non-pneumatic tire.

[0057] The vertical vibration amplitude of the non-pneumatic tire when crossing an obstacle is as follows: Figure 7 , 8 As shown in the figure, it can be seen that with the increase of obstacle height and obstacle traversal speed, the peak amplitude of the tire vertical vibration and most of the amplitudes in the entire frequency domain increase significantly, that is, the local and overall vibration intensity increases, which is consistent with the fluctuation change law of the tire vertical excitation force.

[0058] The Fast Fourier Transform (FFT) of MATLAB is used to convert the excitation force changes in the time domain into amplitude changes in the frequency domain, and the amplitude is used to determine the intensity of the vertical vibration. Since the sound pressure level (SPL) with a frequency lower than 100Hz has no significant effect on human perception of noise, and the vibration amplitude of the non-pneumatic tire is significantly reduced when the frequency is greater than 1500Hz, the impact on the vibration is small. Therefore, 100Hz-1500Hz is selected as the frequency analysis range of the vibration amplitude. In order to obtain more accurate and intuitive comparison results, the vibration amplitude in the frequency domain is quantified. The root mean square value (RMS) of the amplitude corresponding to all frequencies in the entire frequency domain is taken. The root mean square value of the amplitude reflects the overall vibration intensity of the tire vibration. The calculation formula for the RMS value is:

[0059]

[0060] Where N is the number of vertical excitation force sample points in the frequency domain, x i is the specific excitation force amplitude at the i-th sample point.

[0061] The relationship between the amplitude of the vertical vibration RMS of a non-pneumatic tire and the change of obstacle crossing speed and obstacle height is as follows: Fig. 9 As shown in the figure. It can be seen from the figure that when the obstacle height remains unchanged, increasing the obstacle crossing speed will increase the obstacle crossing impact force and then increase the vibration intensity of the tire; similarly, when the obstacle crossing speed remains unchanged, the vertical vibration intensity of the obstacle crossing increases with the increase of the obstacle height; compared with the increase of the obstacle height or obstacle crossing speed alone, the increase of both at the same time has a more obvious effect on the vertical vibration intensity of the tire. The values ​​after calculating RMS are shown in Table 1.

[0062] Table 1

[0063]

[0064] Step 5: Based on the test data and related analysis content in step 4, analyze and compare the RMS value representing the vibration characteristics of the tire and the σ representing the ground contact pressure characteristics. GPP The correlation is studied, and a method to characterize the vibration smoothness of non-pneumatic tire rolling over obstacles is proposed.

[0065] Step 1: When the speed is 10-30km / h, select obstacle heights of 10-30mm to analyze the vibration characteristics and ground contact characteristics at different vehicle speeds.

[0066] During the obstacle crossing simulation analysis in Step 2, due to the influence of multiple factors such as discrete spokes, obstacle height, obstacle crossing speed, etc., the tire will have different ground contact pressure characteristics at different obstacle crossing positions, which will lead to uneven ground contact pressure. The tire obstacle crossing process is mainly divided into five states: tire obstacle crossing begins (a), contacts the obstacle (b), is completely on the obstacle (c), is about to leave the obstacle (d), and the obstacle crossing ends (e). Fig.10 As shown. The obstacle crossing start state is that the rolling non-pneumatic tire is 1-2 meters away from the obstacle, the obstacle contact state is that the non-pneumatic tire tread is in contact with one side of the obstacle and the tread does not bend or deform at this time; the obstacle completely on the obstacle state is that the width of the obstacle is completely covered by the non-pneumatic tire tread and the tread deformation is the largest at this time; the obstacle separation state is that the non-pneumatic tire tread is separated from the obstacle and no bending or deformation occurs at this time; the obstacle crossing end state is that the non-pneumatic tire is 2-3 meters away from the obstacle;

[0067] Step 3 takes the five steps as the analysis steps of the grounding characteristics, extracts the peak grounding pressure of the tire in each step, and takes the standard deviation of the grounding pressure peaks of the five steps (Standard Deviation of Grounding Pressure Peaks, σ GPP ), using σ GPP The value represents the fluctuation of the tire ground pressure during the obstacle crossing process, σ GPP The larger the value, the greater the fluctuation of the tire's ground pressure and the more unstable it is. GPP The value is calculated as follows:

[0068]

[0069] In the formula, μ is the value x 1 …x N The average value, x i is the ground pressure peak value under five conditions, i=5.

[0070] Step 4 analyzes the vertical vibration intensity of non-pneumatic tires, which increases with the increase of vehicle speed and load on flat ground; the vertical vibration intensity of tires increases with the increase of obstacle height and obstacle crossing speed.

[0071] Step 5: Peak ground pressure of a non-pneumatic tire when it passes over the same obstacle at different speeds with a height of 30 mm, σ GPP The values ​​are shown in Table 2. The peak ground pressure of a non-pneumatic tire when it passes over different obstacles at a speed of 20 km / h, σ GPP The values ​​are shown in Table 3. It can be seen that the σ GPPThe values ​​increase with the increase of obstacle height, which means that the increase of obstacle height increases the ground pressure fluctuation of tire when crossing the obstacle and increases the instability of tire ground contact. Correspondingly, from the variation law of vertical vibration amplitude with speed and obstacle height, it can be seen that the vertical vibration intensity of non-pneumatic tire also increases with the increase of obstacle height. GPP The value can reasonably explain the effect of the height change of the obstacle on the intensity of the obstacle crossing vibration, that is, the higher the obstacle height, the greater the obstacle crossing σ GPP The larger the value, the greater the fluctuation of the tire's ground contact pressure during obstacle crossing, and the more intense the tire's obstacle crossing vibration intensity.

[0072] Table 2

[0073]

[0074] Table 3

[0075]

[0076] Step 6 focuses on analyzing the correlation between the obstacle grounding pressure characteristics and the vibration characteristics as well as σ GPP The correlation with the RMS value shows that the standard deviation of the ground pressure peak value σ at the same speed and different obstacle heights is GPP The correlation of the RMS of the obstacle crossing vibration intensity can be reasonably explained, and there is a positive correlation between the two, such as Fig.12 ; When the obstacle height is the same and the obstacle crossing speed is different, the standard deviation of the obstacle crossing ground pressure peak value σ GPP It is positively correlated with RMS, such as Fig.13 .

[0077] Step 7 The standard deviation of the ground pressure peak value in the obstacle crossing process is positively correlated with the RMS. Therefore, the standard deviation of the ground pressure peak value in the five states is obtained during the obstacle crossing process. GPP It can be reasonably explained that the intensity of obstacle crossing vibration changes with the increase or decrease of obstacle height, and there is a positive correlation between the two. The obstacle crossing vibration smoothness of non-pneumatic tires can be analyzed by analyzing the standard deviation of the ground contact pressure peak σ GPP To judge; and the standard deviation of the peak value of the ground pressure over the obstacle σ GPP The positive correlation with RMS can also help determine the smoothness of the vibration of a non-pneumatic tire over an obstacle.

[0078] Therefore, when studying the vibration smoothness of non-pneumatic tires when crossing obstacles, we can combine σ GPP The relationship with the RMS value is used to analyze the vibration smoothness of obstacle crossing.

[0079] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0080] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined in this specification may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for characterizing the vibration smoothness of a non-pneumatic tire rolling over obstacles, characterized in that: The following steps are involved: Step 1: Establish an initial non-pneumatic tire model, and establish a three-dimensional model of the tire according to the outer contour parameters of the non-pneumatic tire; Step 2: Construct a tire obstacle crossing simulation analysis model to analyze the flat ground obstacle crossing behavior of non-pneumatic tires. The obstacle crossing process is divided into five states: tire obstacle crossing starts (a), contacts the obstacle (b), is completely on the obstacle (c), is about to leave the obstacle (d), and ends the obstacle crossing (e). The standard deviation σ of the tire ground contact pressure peak value in the five states is obtained. GPP ; Step 3: Design a test plan. Take tire speed and obstacle height as variables to design a test plan. Take the root mean square (RMS) value of the vertical excitation force of the road contact force in the frequency domain as the target response value. Perform simulation analysis on the obstacle crossing process of non-pneumatic tires for different design experimental plans to obtain the target response value under each obstacle crossing condition. Step 4: Analyze the standard deviation σ of the ground pressure peak using statistical analysis methods GPP , and the relationship between the RMS value of the vertical excitation force; Step 5: Obtain a characterization method for the ride comfort of a non-pneumatic tire when crossing obstacles of different obstacle heights, based on the standard deviation of the peak ground contact pressure σ GPP The positive correlation with the root mean square RMS and the standard deviation of the ground pressure peak value obtained in the five states during the obstacle crossing process indicate that the obstacle crossing vibration intensity changes with the increase or decrease of the obstacle height. By analyzing the standard deviation of the ground pressure peak value σ GPP To judge the vibration smoothness of non-pneumatic tires over obstacles; The standard deviation σ of the ground pressure peaks in the five states is GPP , using σ GPP The value represents the fluctuation of the tire ground pressure during the obstacle crossing process, and the standard deviation σ GPP The value is calculated as follows: In the formula, μ is the value x1…x N The average value, x i is the ground pressure peak value under five conditions, i=5.

2. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 1, characterized in that: The non-pneumatic tire structural parameters in step 1 include wheel hub diameter, tire width, flexible ring thickness, tread thickness, spoke thickness, spoke curvature, and spoke quantity.

3. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 1, characterized in that: In the step 2, the Abaqus / Explicit method is used to constrain the vertical freedom of the tire, and a vertical load is applied to the tire through the road. The established non-pneumatic tire is subjected to different speeds to extract the vertical road excitation force in the time domain during the non-pneumatic tire's obstacle crossing process, and the road vertical excitation force in the frequency domain is obtained by Fourier transform. The root mean square RMS of the road vertical excitation force in the frequency domain is used to perform vibration and smoothness analysis of the non-pneumatic tire rolling obstacle crossing, wherein the calculation formula of the root mean square RMS value of the road vertical excitation force is: Where N is the number of vertical excitation force sample points in the frequency domain, x i is the specific excitation force amplitude at the i-th sample point.

4. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 3, characterized in that: The five states in the step 2 are specifically: the obstacle crossing start state is that the rolling non-pneumatic tire is 1-2 meters away from the obstacle; the obstacle contact state is that the tread of the non-pneumatic tire is in contact with one side of the obstacle and the tread does not undergo any bending or deformation at this time; the completely on the obstacle state is that the width of the obstacle is completely covered by the tread of the non-pneumatic tire and the tread deformation is maximum at this time; the obstacle separation state is that the tread of the non-pneumatic tire is separated from the obstacle and no bending or deformation occurs at this time; the obstacle crossing end state is that the non-pneumatic tire is 2-3 meters away from the obstacle.

5. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 1, characterized in that: In the step 3, the obstacle height during the tire driving process ranges from 10 mm to 30 mm, and the driving speed ranges from 10 km / s to 30 km / s.

6. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 1, characterized in that: The statistical experimental design method in step 4 is a full-factor experimental design method, and the root mean square (RMS) value of the vertical excitation force during the tire obstacle crossing process under different experimental design schemes and the ground contact pressure peaks under five states are obtained through numerical simulation.

7. The method for characterizing the rolling obstacle vibration smoothness of a non-pneumatic tire according to claim 6, characterized in that: The functional relationship in step 4 is a changing relationship established based on the root mean square (RMS) value of the vertical excitation force of the tire obstacle crossing vibration characteristics, the obstacle height, and the driving speed.

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