Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Oct 2019

Physical Understanding of Transient Generation of Tire Lateral Force and Aligning Torque

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Page Range: 308 – 333
DOI: 10.2346/tire.19.180192
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ABSTRACT

Increasing vehicle performance requirements and virtualization of the development process require more understanding of the physical background of tire behavior, especially in transient rolling conditions with combined slip. The focus of this research is the physical description of the transient generation of tire lateral force and aligning torque. Apart from tire force and torque measurements, two further issues were investigated experimentally. Using acceleration measurement on the tire inner liner, it was observed that the contact patch shape of the rolling tire changes nonlinearly with slip angle and becomes asymmetric. Optical measurement outside and inside the tire has clarified that carcass lateral bending features both shear and rotation angle of its cross sections. A physical simulation model was developed that considers the observed effects. The model was qualitatively validated using not only tire force and torque responses but also deformation of the tire carcass. The model-based analysis explained which tire structural parameters are responsible for which criteria of tire performance. Change in the contact patch shape had a low impact on lateral force and aligning torque. Variation of carcass-bending behavior perceptibly influenced aligning torque generation.

Keywords: physical tire model; transient behavior; tire lateral bending; contact patch shape
FIG. 1
FIG. 1

Structural scheme of the extended string model [7].

FIG. 2
FIG. 2

Top view on the string model, a representation of [8].

FIG. 3
FIG. 3

Multirow representation of the Treadsim model [7].

FIG. 4
FIG. 4

Contact patch of a cornering tire [14].

FIG. 5
FIG. 5

Estimation of the tire contact patch shape with several acceleration sensors.

FIG. 6
FIG. 6

Footprint of a stationary tire (gray) and leading and trailing edges while cornering (black). Wheel load was 7 kN; slip angle was 3°.

FIG. 7
FIG. 7

The nonlinear connection between contact patch length and slip angle. Wheel load was 7 kN; slip angle was 3°.

FIG. 8
FIG. 8

The setup for optical measurement of carcass lateral deflection.

FIG. 9
FIG. 9

Separation of carcass deflection from tread shear deformation.

FIG. 10
FIG. 10

“Lateral force – lateral displacement” diagrams.

FIG. 11
FIG. 11

Carcass deflection due to lateral excitation.

FIG. 12
FIG. 12

Carcass deflection due to torsional excitation.

FIG. 13
FIG. 13

Different assumptions for the bending behavior of carcass.

FIG. 14
FIG. 14

Measurement of distance between markers on the shoulder edge of the cornering tire.

FIG. 15
FIG. 15

Analysis of the observed bending behavior compared with the two hypotheses.

FIG. 16
FIG. 16

Elements of the proposed physical tire model.

FIG. 17
FIG. 17

Consideration of the relevant physical properties in the tire model.

FIG. 18
FIG. 18

Calculation of coordinates of the brush elements on the deflected carcass body.

FIG. 19
FIG. 19

Model validation based on tire response to slip angle excitation.

FIG. 20
FIG. 20

Model validation based on response of cornering tire to wheel load excitation.

FIG. 21
FIG. 21

Model validation based on tire response to combined overlapping excitation.

FIG. 22
FIG. 22

Simulation of the load case “slip angle step” with constant and variable contact patch shape.

FIG. 23
FIG. 23

Simulation of the load case “slip angle step” with different carcass shear angle coefficients.

FIG. 24
FIG. 24

Simulation of the load case “torsional excitation” with considered and neglected distributed bending torque on the carcass.

Contributor Notes

2 Corresponding author. Email: pavel.sarkisov@web.de
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