Editorial Type:
Article Category: Research Article
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Online Publication Date: 15 Oct 2024

Tire Performance and Testing under Longitudinal and Combined Slip States: Induced vs Resultant Wheel-Related Slip

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Page Range: 170 – 192
DOI: 10.2346/260832
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ABSTRACT

Tires influence many overall vehicle characteristics, including safety, performance, comfort, and handling. Testing is needed to characterize tires for the selection of original equipment manufacturers submissions as well as for the development of other suspension and chassis components. The reality that tire responses are highly nonlinear and change significantly with temperature, wear, and surface pairing makes testing to adequately characterize tires for vehicle development difficult. Furthermore, achieving robust, repeatable braking and driving measurements is particularly challenging. Unlike cornering tests, the test rig input is directly opposed to the tire response vector. Moreover, using an estimated parameter (e.g., slip ratio) as a control value prohibits a clear distinction between the linear test rig input and the nonlinear tire response. In this paper, the influence of the wheel-related slip control on tire performance under longitudinal and combined slip conditions is investigated. Two different tire types are measured in a laboratory environment on an MTS Flat-Trac CT+ tire test rig. A variety of test procedures are used to consider the influence of slip and torque rates under different operating conditions (e.g., wheel loads). A recommendation is given for a low-wear and cost-efficient testing methodology for an improved assessment of tire longitudinal and combined slip characteristics by using a linear test rig input.

Keywords: longitudinal slip; combined slip; tire testing; Flat-Trac
FIG. 1 —
FIG. 1 —

Exemplary force slip characteristic curve.

FIG. 2 —
FIG. 2 —

Example of induced wheel SR control with two SR rates.

FIG. 3 —
FIG. 3 —

Example of resultant wheel SR control with two torque rates.

FIG. 4 —
FIG. 4 —

MTS Flat-Trac IV CT+ tire test rig including temperature measurement equipment.

FIG. 5 —
FIG. 5 —

Exemplary evaluation procedure for assessing tire performance.

FIG. 6 —
FIG. 6 —

Pure longitudinal slip characteristic curves with tire type A (left) and tire type B (right).

FIG. 7 —
FIG. 7 —

Evaluated characteristics for quasi-stationary longitudinal slip states.

FIG. 8 —
FIG. 8 —

Tire thermal state across multiple test conditions.

FIG. 9 —
FIG. 9 —

Input rate over time.

FIG. 10 —
FIG. 10 —

Evaluation results obtained with tire type A.

FIG. 11 —
FIG. 11 —

Combined slip characteristic curves with tire type A (left) and tire type B (right).

FIG. 12 —
FIG. 12 —

Evaluated characteristics for quasi-stationary combined slip states.

FIG. 13 —
FIG. 13 —

Tire thermal state across multiple test conditions at low slip angles.

FIG. 14 —
FIG. 14 —

Tire thermal state across multiple test conditions at high slip angles.

FIG. 15 —
FIG. 15 —

Input rate over time for combined slip states.

FIG. 16 —
FIG. 16 —

Longitudinal force and slip signals for each excitation type, measured with tire type A under wheel load Fz3.

FIG. 17 —
FIG. 17 —

Frequency response diagrams generated using data measured with tire type A (left) and tire type B (right) under wheel load Fz3.

FIG. 18 —
FIG. 18 —

Longitudinal relaxation length (σx) by using data measured with tire type A (left) and tire type B (right).

Contributor Notes

1  Corresponding author. Vehicle Dynamics & Acoustics, Institute for Automotive Engineering (ika), RWTH Aachen University, Steinbachstraße 7, Aachen, Nordrhein-Westfalen 52074, Germany. Email: ventseslav.yordanov@ika.rwth-aachen.de
2  Chassis & NVH, fka GmbH, Steinbachstraße 7 Aachen, Nordrhein-Westfalen 52074, Germany
5  EFDD/4, Volkswagen AG, Berliner Ring 2, Wolfsburg, Niedersachsen 38436, Germany. Email: konstantin.sedlan@volkswagen.de
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