Abstract:
In order to simulate vehicle handling and roll over propensities, tyre characteristics in the form of
side-force versus slip-angle curves, as well as suitable tyre models are required. For large tyres
these characteristics are not readily available. Tyre manufacturers either do not have these
characteristics, or do not openly publish them.
Similarly, the majority of tyre models have been developed and validated for passenger car tyres
and their applicability to large tyres are unknown. Furthermore the tests conducted to obtain
passenger car tyre data cannot always be performed on large tyres.
The purpose of this study was to measure side-force versus slip-angle characteristics for two
large tyres then use the data to parameterise existing tyre models and determine the accuracy of
these models. The tyres of interest were the GoodYear Regional 385/65R22.5 tyre, which is a
typical truck tyre, and a Michelin 16.00R20 XZL, which is a tyre typically used on military vehicles.
In order to measure these characteristics, existing tyre testing equipment in the form of a tyre test
trailer had to be revived, as it had not been used in the past 10 years. The confidence in the
equipment was therefore so low that extensive verification tests had to be conducted to develop
sufficient confidence in the equipment, to be able to perform these tests and obtain accurate data.
In line with this objective, it was envisaged to create a commercial business opportunity for tyre
testing utilising the revived equipment, as there is a huge international requirement for data on
these tyres.
The above equipment revival was conducted successfully, and the tyre tests were performed at
Gerotek Test Facilities. Successful steady state side-force versus slip-angle characteristic tests
were performed, and a dynamic double lane change test was performed, and used to validate
models.
From the side-force versus slip-angle characteristic data three existing tyre models were
parameterised namely, Fiala, UA (University of Arizona) and Pacejka 89 tyre models, as
implemented in ADAMS View software.
In order to validate these models, an ADAMS model of the Tyre Tester was developed
incorporating physical measured parameters, such as the geometry, mass, centre of mass and
moments of inertia.
Correlation between the simulated data of the tyre models and the measured track data was
evaluated. The correlation showed that the Pacejka 89 tyre model provided the closest fit for the
side-force versus slip angle tests, of all three tyre models. The Pacejka 89 tyre model also
showed good correlation on the dynamic double lane change tests.
