CN108460180B - Tire longitudinal and transverse stiffness simulation method considering elastic slippage - Google Patents

Abstract

The invention discloses a tire longitudinal and lateral stiffness simulation method considering elastic slip, comprising the steps of: performing finite element modeling on a three-dimensional nonlinear tire; and performing initial simulation analysis on the longitudinal or lateral stiffness of the tire based on the model. The tangential contact attribute with the ground adopts the default constitutive attribute of the penalty function method, and its allowable elastic slip tolerance is 0.005; select the node on the longitudinal or lateral centerline of the tire contact patch in the initial simulation results, and output the node and The longitudinal or lateral displacement of the road reference point over time determines the maximum elastic slip of the selected node during the longitudinal or lateral deformation of the tire; modify the initial simulation model of the tire longitudinal and lateral stiffness finite element, that is, in the tangential contact constitutive The maximum elastic slippage is introduced into the properties, and the longitudinal or lateral stiffness simulation analysis of the tire is performed again. After considering the elastic slip in the present invention, the reliability of the tire longitudinal and lateral stiffness simulation results will be greatly improved.

Description

A Simulation Method of Tire Longitudinal and Lateral Stiffness Considering Elastic Slip

technical field

The invention relates to a finite element simulation method for longitudinal and transverse stiffness of tires, in particular to a method for improving the simulation accuracy of longitudinal and transverse stiffness of tires by introducing elastic slippage into tangential contact properties.

Background technique

The stiffness characteristics of the tire refer to the relationship between the load acting on the tire and the corresponding deformation, including the tire radial, lateral, longitudinal, torsional and wrapping stiffness. Predicting the stiffness characteristics of tires through finite element simulation plays an important role in promoting the optimal design of tire structures.

With the development of finite element theory, the tire stiffness simulation technology has gradually matured. Many scholars have used different finite element software to analyze the tire stiffness, and they have obtained reasonable results. However, in the process of stiffness benchmarking, the simulation results of radial stiffness and cladding stiffness are relatively accurate, while the longitudinal and transverse stiffness simulation results involving adhesion and friction behavior are quite different from the experimental results. For example, Yan Liang (Yan Liang. Modelling of tire cornering and roll characteristics based on discretization of carcass finite element model [D]. Master Thesis of Jilin University. 2014) and Bai Fan (Bai Fan. Tire mechanics model based on ground contact patch analysis) Research [D]. Doctoral dissertation of Jilin University. 2016), the simulation results of longitudinal and lateral stiffness of tires are significantly higher than the experimental results. Figure 1 shows the comparison between the simulation analysis of tire longitudinal stiffness and the test results.

分别为总滑移、弹性滑移、塑性滑移。其核心思想是将切向滑移过程分为弹性滑移和塑性滑移两部分[Peter Wriggers.ComputationalContact Mechanics.Springer,Berlin,Second Edition.2006.]。For the tangential contact between two rough surfaces, based on the classical Coulomb friction theory, some scholars put forward an extended friction theory. These include the regularized Coulomb friction law based on elastoplastic slip theory, which can approximately describe stick-slip motion, as shown in Figure 2,

They are total slip, elastic slip, and plastic slip, respectively. The core idea is to divide the tangential slip process into two parts: elastic slip and plastic slip [Peter Wriggers.ComputationalContact Mechanics.Springer,Berlin,Second Edition.2006.].

In ABAQUS finite element analysis software, when elastic slip is considered in tangential contact, in addition to defining the elastic slip tolerance, it is also possible to directly define the maximum elastic slip to realize the elastic-plastic simulation of tangential contact. However, it is difficult to determine the maximum amount of elastic slip because there is no experimental or empirical data to know the amount of elastic slip between the tire and the road surface. Different elastic slip amounts are produced when slipping. Therefore, for the simulation of tire longitudinal or lateral stiffness, not only the influence of elastic slip, but also how to determine the amount of elastic slip should be considered.

SUMMARY OF THE INVENTION

The invention proposes a tire longitudinal and lateral stiffness simulation method considering elastic slip. The maximum elastic slip is determined through the initial simulation analysis results, and the initial simulation model of the tire longitudinal or lateral stiffness finite element is modified, that is, in the tangential contact constitutive property Introduce the maximum elastic slip in the simulation analysis of tire longitudinal or lateral stiffness again.

The present invention adopts the following technical scheme to realize:

A tire longitudinal and lateral stiffness simulation method considering elastic slip, including steps:

Finite element modeling of 3D nonlinear tires;

Based on the established model, the initial simulation analysis of longitudinal or lateral stiffness of the tire is carried out. At this time, the tangential contact property between the tire and the ground adopts the default constitutive property of the penalty function method, and the allowable elastic slip tolerance is 0.005;

Select the nodes on the longitudinal or lateral centerline of the tire contact patch in the initial simulation results, output the longitudinal or lateral displacements of the nodes and road reference points over time, and determine the maximum elastic slip of the selected nodes during the longitudinal or lateral deformation of the tire. ;

Modify the initial simulation model of the tire longitudinal and lateral stiffness finite element, that is, introduce the maximum elastic slip in the tangential contact constitutive properties, and perform the longitudinal or lateral stiffness simulation analysis of the tire again.

Further, the process of determining the maximum elastic slippage of each node selected during the longitudinal deformation of the tire specifically includes the steps:

After the initial simulation calculation is completed, select the nodes on the longitudinal centerline of the tire in the contact patch, output the displacement curve of the selected node and the road reference point with time, and obtain the transition process of the tire nodes from elastic slip to plastic slip in the contact area. ;

Select the node with the largest elastic slip, determine the displacement of the node when plastic slip starts to occur, and determine the difference between the displacement of the road reference point and the displacement of the node as the maximum elastic slip.

Further, when there are more than two nodes selected, at least one node is located on the tire longitudinal centerline on the rear end boundary of the contact patch along the advancing direction of the wheel.

Further, when the selected node is one, the node is located on the tire longitudinal centerline on the rear end boundary of the contact patch along the wheel advancing direction.

Further, the process of determining the maximum elastic slippage of each node selected during the lateral deformation of the tire specifically includes the steps:

After the initial simulation calculation is completed, select the nodes on the lateral centerline of the tire in the contact patch, output the displacement curve of the selected nodes with time, and obtain the transition process of the tire nodes from elastic slip to plastic slip in the contact area;

Select the node with the largest elastic slip, determine the displacement of the node when plastic slip starts to occur, and determine the difference between the displacement of the road reference point and the displacement of the node as the maximum elastic slip.

Further, when there are more than two nodes selected, at least one node is located on the tire lateral centerline on the rear end boundary of the contact patch along the advancing direction of the wheel.

Further, when the selected node is one, the node is located on the tire lateral centerline on the rear end boundary of the contact patch along the wheel advancing direction.

Further, the step of determining that the node begins to undergo plastic slip specifically includes:

When the selected node slides relative to the road surface, and the node displacement does not increase any more, it means that the elastic deformation of the node reaches saturation, the elastic slip phase ends, and the plastic slip begins.

Further, in the step of outputting the displacement change curve of the selected node over time, after outputting the displacement change data, the data is preprocessed, that is, the initial displacement of the selected node is zeroed, which is convenient for comparison and observation. Determine the maximum elastic slip.

Further, the simulation analysis is based on ABAQUS finite element analysis software.

Compared with the prior art, the present invention introduces the maximum elastic slip into the tangential contact constitutive property, and performs the tire longitudinal or lateral stiffness simulation analysis again, so that the reliability of the tire longitudinal and lateral stiffness simulation results is greatly improved; By introducing elastic slip, the elastic-plastic slip behavior of tire tangential motion is simulated approximately, and more reliable tire longitudinal and lateral stiffness simulation results are obtained.

Description of drawings

Figure 1. Comparison curve of longitudinal stiffness simulation test.

Fig. 2 Schematic diagram of tangential slip segmentation.

FIG. 3 is a schematic diagram of the distribution of nodes selected by the centerline displacement of the grounding area according to an embodiment of the present invention.

FIG. 4 is a time history curve of each longitudinal node and road surface displacement according to an embodiment of the present invention.

Fig. 5 Comparison of longitudinal stiffness simulation and test with or without the definition of the maximum elastic slip.

Fig. 6 Comparison of lateral stiffness simulation and experiment with or without the definition of the maximum elastic slip.

Detailed ways

The purpose of the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be repeated here, but the embodiments of the present invention are not limited to the following embodiments.

The following takes the simulation analysis of the longitudinal stiffness of the 215/60R16 tire as an example to further illustrate the implementation of the present invention.

A tire longitudinal and lateral stiffness simulation method considering elastic slip, including steps:

Step 1: Based on the ABAQUS finite element analysis software, the three-dimensional nonlinear tire is subjected to finite element modeling.

Step 2: Initial simulation analysis to determine the maximum elastic slippage in the contact area.

Based on the established model, the initial simulation analysis of longitudinal or lateral stiffness of the tire is carried out. At this time, the tangential contact attribute between the tire and the ground adopts the default constitutive attribute of the penalty function method. In the definition of the contact between the tire and the ground, the tangential contact attribute defines the elasticity The slip tolerance is 0.005 by default.

After maintaining the tire pressure of 0.23Mpa and fixing the rim, radially move the road surface to realize the loading of the tire under the specified load, and then move the road surface longitudinally to realize the longitudinal loading.

After the longitudinal loading simulation analysis is completed, open the generated result file, as shown in Figure 3, select three nodes a, b, and c in the direction of the longitudinal centerline from right to left at the contact patch, and the tire moves to the left relative to the road surface. The a node is located on the rear boundary of the contact patch along the wheel advancing direction, the c node is located on the front boundary of the contact patch along the wheel advancing direction, and the b node is located at the center of the contact patch along the wheel advancing direction.

Output the longitudinal displacement of the above selected nodes and the displacement history of the road reference point, and subtract the initial displacement caused by the radial loading of the tire to obtain the displacement history curve of each node and road surface with time as shown in Figure 4.

It can be seen from Figure 4 that the displacement changes linearly during the longitudinal movement of the road surface. In the interval of 0-4mm of road surface displacement, the displacement history of the tread nodes and the road surface basically coincide, which means that there is basically no relative slippage during the initial longitudinal deformation of the tire. After the road surface is displaced by 4 mm, the node a on the rear end boundary of the ground contact along the advancing direction of the wheel first produces relative slippage with the road surface, that is, elastic slippage. Then other nodes of the tread also slip relative to the road surface one after another, and the length of the longitudinal elastic slip zone of the tread gradually expands. Until the road surface moves to 19.2mm, the displacement of all nodes of the tread reaches saturation, indicating that the longitudinal elastic deformation of the carcass reaches the maximum, and the tire begins to slide plastically relative to the road surface. At this time, the displacement of node a is 14.07mm. Before this node is in the elastic slip zone, and after the displacement reaches saturation, it is in the plastic slip zone. Under this displacement, the elastic slippage of the node relative to the road surface reaches the maximum 19.2-14.07=5.13mm. Thus, the maximum elastic slippage generated when the tire slips longitudinally is 5.13 mm.

In the same way, it is determined that the maximum elastic slippage generated when the tire slips laterally is 6.5mm.

Step 3: Modify the initial simulation model of the tire longitudinal and lateral stiffness finite element, that is, the maximum elastic slip generated when the tire longitudinal slip is 5.13mm and the maximum tire lateral slip generated by introducing the resulting tangential contact constitutive properties The elastic slippage is 6.5mm, and the longitudinal or lateral stiffness simulation analysis of the tire is performed again.

Comparing the results of the longitudinal or lateral stiffness simulation analysis of the tire again with the simulation results and experimental results without considering the elastic slip, the graphs shown in Figure 5 and Figure 6 are obtained. Simulation analysis, when considering the maximum elastic slip of the tire and the ground, can significantly improve the simulation analysis accuracy of the longitudinal and lateral stiffness of the tire.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (9)

1. A method for simulating the longitudinal and transverse stiffness of a tyre taking into account elastic slip, characterized in that it comprises the steps of:

finite element modeling is carried out on the three-dimensional nonlinear tire;

performing initial simulation analysis on the longitudinal or transverse stiffness of the tire based on the established model, wherein the tangential contact attribute between the tire and the ground adopts the default constitutive attribute of a penalty function method, and the allowable elastic slip tolerance is 0.005;

selecting nodes on the longitudinal or transverse center line of the tire contact patch in the primary simulation result, outputting the longitudinal or transverse displacement of the nodes and a road reference point along with the change of time, and determining the maximum elastic slippage of the selected nodes in the longitudinal or transverse deformation process of the tire;

modifying the initial simulation model of the finite element of the longitudinal and transverse stiffness of the tire, namely introducing the maximum elastic slippage in the tangential contact constitutive property, and carrying out simulation analysis on the longitudinal or transverse stiffness of the tire again;

the process for determining the maximum elastic slippage of each selected node in the tire longitudinal deformation process specifically comprises the following steps:

after the initial simulation calculation is completed, selecting nodes on the longitudinal center line of the tire in the grounding trace, and outputting displacement change curves of the selected nodes and the road surface reference point along with time to obtain the process of the transition of the tire nodes in the grounding area from elastic slip to plastic slip;

and selecting a node with the largest elastic slip, determining the displacement of the node when the node starts to generate plastic slip, and determining the difference between the displacement of the road surface reference point and the displacement of the node as the maximum elastic slip.

2. A method for simulating the longitudinal and transverse stiffness of a tire taking elastic slip into account as claimed in claim 1, characterized in that as a whole: when the number of the selected nodes is two or more, at least one node is located on the tire longitudinal center line on the rear end boundary of the footprint in the wheel advancing direction.

3. A method for simulating the longitudinal and transverse stiffness of a tire taking elastic slip into account as claimed in claim 1, characterized in that as a whole: when the selected node is one, the node is located on the tire longitudinal centerline on the rear end boundary of the footprint in the wheel advancing direction.

4. A method for simulating the longitudinal and transverse stiffness of a tire taking elastic slip into account as claimed in claim 1, characterized in that as a whole: the process for determining the maximum elastic slippage of each selected node in the tire lateral deformation process specifically comprises the following steps:

after the initial simulation calculation is completed, selecting nodes on the transverse center line of the tire in the grounding trace, and outputting a displacement change curve of the selected nodes along with time to obtain a process of changing the nodes of the tire in the grounding area from elastic slip to plastic slip;

and selecting a node with the largest elastic slip, determining the displacement of the node when the node starts to generate plastic slip, and determining the difference between the displacement of the road surface reference point and the displacement of the node as the maximum elastic slip.

5. Method for simulating the longitudinal and transverse stiffness of a tyre taking account of the elastic displacements according to claim 4, characterized in that, overall: when the selected node is two or more, at least one node is located on the tire lateral center line on the rear end boundary of the footprint in the wheel advancing direction.

6. Method for simulating the longitudinal and transverse stiffness of a tyre taking account of the elastic displacements according to claim 4, characterized in that, overall: when the selected node is one, the node is located on the tire lateral center line on the rear end boundary of the footprint in the wheel advancing direction.

7. Method for simulating the longitudinal and transverse stiffness of a tyre taking account of elastic slip according to claim 1 or 4, characterized in that the step of determining the onset of plastic slip at the node point comprises in particular:

when the selected node slides relative to the road surface and the displacement of the node is not increased any more, the elastic deformation of the node is saturated, the elastic sliding stage is finished, and the plastic sliding starts.

8. Method for simulating the longitudinal and transverse stiffness of a tyre taking account of elastic slippage according to claim 1 or 4, characterized in that: in the step of outputting the displacement change curve of the selected node along with the time, after the displacement change data is output, preprocessing the data, namely performing zeroizing processing on the initial displacement of the selected node, so that comparison and observation are facilitated to determine the maximum elastic slippage.

9. A method of simulating longitudinal and transverse stiffness of a tire taking into account spring slippage as claimed in claim 1, wherein said simulation analysis is based on ABAQUS finite element analysis software.

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