CN108460180A - A kind of tire vertical and horizontal rigidity simulation method considering elastic slip - Google Patents

Abstract

The invention discloses a kind of tire vertical and horizontal rigidity simulation methods considering elastic slip, including step：Finite element modeling is carried out to the tire of three dimensional non-linear；The vertical or horizontal initial simulation analysis of rigidity is carried out to tire based on model, the tangential contact attribute between tire and ground uses the acquiescence of penalty function method this structure attribute at this time, and the elastic slip tolerance allowed is 0.005；The node on the vertical or horizontal center line of tire ground contact patch in first simulation result is chosen, the vertical or horizontal displacement that output node and road surface reference point change over time determines the maximum flexibility slippage that selected node occurs in the vertical or horizontal deformation process of tire；The initial simulation model of tire vertical and horizontal rigidity finite element is changed, i.e., introduces maximum flexibility slippage in tangentially contacting this structure attribute, carries out the vertical or horizontal rigidity simulation analysis of tire again.After the present invention considers elastic slip, the reliability of tire vertical and horizontal rigidity simulation result will have to be promoted by a relatively large margin.

Description

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

technical field

The invention relates to a finite element simulation method of tire longitudinal and lateral rigidity, specifically a method for improving the simulation accuracy of tire longitudinal and lateral rigidity by introducing elastic slip into tangential contact properties.

Background technique

The stiffness characteristics of a tire refer to the relationship between the load acting on the tire and the corresponding deformation, including the radial, transverse, longitudinal, torsional, and wrapping stiffness of the tire. 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, tire stiffness simulation technology has gradually matured. Many scholars have used different finite element software to analyze tire stiffness, and all 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 simulation results of longitudinal and transverse stiffness involving adhesion and friction behavior are quite different from the experimental results. For example, Yan Liang (Yan Liang. Discretization of carcass finite element model research on tire cornering and roll characteristics modeling [D]. Master's thesis of Jilin University. 2014) and Bai Fan (Bai Fan. Tire mechanics model based on contact patch analysis Research [D]. Jilin University Doctoral Thesis. 2016) The tire longitudinal and lateral stiffness simulation results are significantly higher than the test results. Figure 1 shows the comparison between the tire longitudinal stiffness simulation analysis and test results.

Aiming at the tangential contact between two rough surfaces, some scholars put forward an extended friction theory based on the classical Coulomb friction theory. These include the regularized Coulomb friction law based on the elastic-plastic slip theory, which can approximately describe the stick-slip motion, as shown in Figure 2, They are total slip, elastic slip, and plastic slip, respectively. Its core idea is to divide the tangential slip process into two parts, elastic slip and plastic slip [Peter Wriggers. Computational Contact 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, the maximum elastic slip can also be directly defined to realize elastic-plastic simulation of tangential contact. However, it is difficult to determine the maximum elastic slip, because there is no experimental or empirical data to know the size of the elastic slip between the tire and the road, different tire specifications and different road conditions, the tire relative to the road tangential Different amounts of elastic slippage are produced when slipping. Therefore, for the simulation of tire longitudinal or lateral stiffness, not only the influence of elastic slip should be considered, but also how to determine the amount of elastic slip should be considered.

Contents of the invention

The present invention proposes a tire longitudinal and lateral stiffness simulation method considering elastic slip, determines the maximum elastic slip through the initial simulation analysis results, and modifies the tire longitudinal or lateral stiffness finite element initial simulation model, that is, in the tangential contact constitutive property Introduce the maximum elastic slip, and then carry out the tire longitudinal or lateral stiffness simulation analysis again.

The present invention adopts following technical scheme to realize:

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

Finite element modeling of 3D nonlinear tires;

Based on the built model, the initial simulation analysis of the 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, and the allowable elastic slip tolerance is 0.005;

Select the nodes on the longitudinal or lateral centerline of the tire contact footprint in the initial simulation results, output the longitudinal or lateral displacement of the nodes and the reference point of the road surface over time, and determine the maximum elastic slip of the selected nodes during the longitudinal or lateral deformation of the tire ;

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

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

After the initial simulation calculation is completed, the nodes on the longitudinal centerline of the tire are selected in the ground contact footprint, and the displacement curves of the selected nodes and the reference point of the road surface are output with time, and the process of the tire nodes in the contact area changing from elastic slip to plastic slip is obtained ;

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

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

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

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

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

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

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

Further, when one node is selected, the node is located on the tire transverse centerline on the rear end boundary of the ground contact footprint along the forward direction of the wheel.

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

When the selected node slides relative to the road surface, and the node displacement does not increase, it indicates 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 nodes over time, after the displacement change data is output, the data is preprocessed first, that is, the initial displacement of the selected nodes is zeroed, so as to facilitate comparative observation and Determine the maximum amount of 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 transverse stiffness simulation analysis again, so that the reliability of the tire longitudinal and transverse stiffness simulation results is greatly improved; By introducing the amount of elastic slip, the elastic-plastic slip behavior of tire tangential motion is approximated, and more reliable simulation results of tire longitudinal and lateral stiffness are obtained.

Description of drawings

Fig. 1 Comparison curve of longitudinal stiffness simulation test.

Fig. 2 Schematic diagram of tangential slip segment.

Fig. 3 is a schematic diagram of distribution of nodes selected for midline displacement of the grounded area according to an embodiment of the present invention.

Fig. 4 is the time-history curve of longitudinal nodes and road surface displacement of the embodiment of the present invention.

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

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

Detailed ways

The purpose of the invention of the present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments, and the embodiments cannot be repeated here one by one, but the implementation of the present invention is not therefore limited to the following embodiments.

The implementation of the present invention will be further specifically described below by taking the simulation analysis of the longitudinal stiffness of the 215/60R16 model tire as an example.

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

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

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

Based on the built model, the initial simulation analysis of the 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 elasticity. The slippage tolerance has a default value of 0.005.

After maintaining the tire pressure of 0.23Mpa and fixing the rim, move the road surface radially 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 ground contact mark, and the tire moves to the left relative to the road. Node a is located on the rear boundary of the ground contact footprint along the wheel's forward direction, node c is located on the front boundary of the ground contact print along the wheel's forward direction, and node b is located in the center of the ground contact footprint along the wheel's forward direction.

Output the longitudinal displacement of the above-mentioned selected nodes and the displacement history of the reference point of the road surface, and subtract the initial displacement caused by the radial loading of the tire, and the displacement history curves of each node and road surface over time can be obtained as shown in Figure 4.

It can be seen from Figure 4 that during the longitudinal movement of the road surface, the displacement changes linearly. In the interval of 0-4mm of road surface displacement, the displacement history of the tread nodes and the road surface basically coincides, 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 boundary of the ground contact footprint along the wheel's forward direction first produces relative slip with the road surface, that is, elastic slip. 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 19.2 mm, 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 plastically slide relative to the road surface. At this time, the displacement of node a is 14.07 mm. Before this, the node is in the elastic slip region, and after the displacement reaches saturation, it is in the plastic slip region. Under this displacement, the elastic slippage of the node relative to the road surface reaches a maximum of 19.2-14.07=5.13mm. Thus, the maximum elastic slip produced when the tire longitudinally slips is 5.13 mm.

In the same way, determine that the maximum elastic slip produced when the tire laterally slips is 6.5mm.

Step 3: Modify the initial finite element simulation model of tire longitudinal and transverse stiffness, that is, introduce the maximum elastic slip of 5.13mm produced when the tire is longitudinally slipped and the maximum The elastic slippage is 6.5mm, and the tire longitudinal or lateral stiffness simulation analysis is carried out again.

Comparing the results of tire longitudinal or transverse stiffness simulation analysis again with the simulation results and experimental results without considering elastic slip, the graphs shown in Figure 5 and Figure 6 are obtained. It can be seen from Figure 5 and Figure 6 that after two 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, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. a kind of tire vertical and horizontal rigidity simulation method considering elastic slip, which is characterized in that including step：

Finite element modeling is carried out to the tire of three dimensional non-linear；

The vertical or horizontal initial simulation analysis of rigidity is carried out to tire based on institute's established model, it is tangential between tire and ground at this time It contacts attribute and uses the acquiescence of penalty function method this structure attribute, the elastic slip tolerance allowed is 0.005；

Choose the node on the vertical or horizontal center line of tire ground contact patch in first simulation result, output node and road surface reference The vertical or horizontal displacement that point changes over time determines the maximum bullet that selected node occurs in the vertical or horizontal deformation process of tire Property slippage；

The initial simulation model of tire vertical and horizontal rigidity finite element is changed, i.e., introduces maximum bullet in tangentially contacting this structure attribute Property slippage, again carry out the vertical or horizontal rigidity simulation analysis of tire.

2. the tire vertical and horizontal rigidity simulation method according to claim 1 for considering elastic slip, global feature It is：The determination process for the maximum flexibility slippage that selected each node occurs during the tire linear deformation specifically includes step Suddenly：

After the completion of initial simulation calculation, the node on tyre equatorial line is chosen in ground contact patch, exports selected node With the displacement changing curve of road surface reference point at any time, obtains ground area tire node and changed from elastic slip to plastic flow Process；

The maximum node of elastic slip is selected, determines displacement when plastic flow takes place in the node, and road surface is referred to The difference of the displacement of point and the displacement of the node is determined as maximum flexibility slippage.

3. the tire vertical and horizontal rigidity simulation method according to claim 2 for considering elastic slip, global feature It is：When selected node is more than two, an at least node is located at ground contact patch along the rear end boundary of wheel direction of advance On tyre equatorial line on.

4. the tire vertical and horizontal rigidity simulation method according to claim 2 for considering elastic slip, global feature It is：When selected node is one, it is vertical along the borderline tire in the rear end of wheel direction of advance which is located at ground contact patch To on center line.

5. the tire vertical and horizontal rigidity simulation method according to claim 1 for considering elastic slip, global feature It is：The determination process for the maximum flexibility slippage that selected each node occurs during the tire transversely deforming specifically includes step Suddenly：

After the completion of initial simulation calculation, the node on tire cross central line is chosen in ground contact patch, exports selected node Displacement changing curve at any time obtains the process that ground area tire node changes from elastic slip to plastic flow；

The maximum node of elastic slip is selected, determines displacement when plastic flow takes place in the node, and road surface is referred to The difference of the displacement of point and the displacement of the node is determined as maximum flexibility slippage.

6. the tire vertical and horizontal rigidity simulation method according to claim 5 for considering elastic slip, global feature It is：When selected node is more than two, an at least node is located at ground contact patch along the rear end boundary of wheel direction of advance On tire cross central line on.

7. the tire vertical and horizontal rigidity simulation method according to claim 5 for considering elastic slip, global feature It is：When selected node is one, it is horizontal along the borderline tire in the rear end of wheel direction of advance which is located at ground contact patch To on center line.

8. the tire vertical and horizontal rigidity simulation method of the consideration elastic slip according to claim 2 or 5, feature exist In determining that the step of plastic flow takes place in the node specifically includes：

When the opposite road surface sliding of selected node, and modal displacement size is not further added by, then shows that node elastic deformation reaches Saturation, elastic slip stage terminate, and plastic flow starts.

9. the tire vertical and horizontal rigidity simulation method of the consideration elastic slip according to claim 2 or 5, feature exist In：In the step of displacement changing curve at any time of node selected by the output, after output displacement delta data, first to data It is pre-processed, i.e., zeroization processing is carried out to the initial displacement of selected node, convenient for paired observation to determine maximum flexibility Slippage.

10. the tire vertical and horizontal rigidity simulation method according to claim 1 for considering elastic slip, feature exist In the simulation analysis is based on ABAQUS finite element analysis softwares.