Estimation of Tire Friction Potential Characteristics by Slip Based On-Road Test Using WFT 2015-26-0225

The tire is generally characterized on the basis of forces and moments being generated at the contact patch, which describes the friction potential of the tire in both longitudinal and lateral directions at different load conditions. The field conditions and applications under which the tires (especially commercial one) perform is diverse, which results in varied performance for the same product. To understand this there is a need to recognize the range of friction values the tire undergoes in different conditions. Though there are couple of methods and indoor test available to estimate the available friction potential, they are not only deficient in replicating the different real road scenarios but also prove difficult to reproduce different road surfaces. There is also a lack of availability and expense of out door test equipment in India.

A joint project has been undertaken between Apollo Tyres and ARAI, where both have used their technical expertise to work on tire characterization out of road test. A slip-based test approach has been carried out to estimate the available longitudinal tire-road friction potential using the longitudinal slip and forces generated at the tire contact patch during a braking test. The test vehicle was instrumented with wheel force sensors, to measure forces being developed in the tires, along with brake sensors and steering wheel sensors to monitor the amount of brake applied and avoid any lateral slippage. The braking test was carried out by varying speed and load conditions. The measured data was then analyzed to find out the longitudinal friction potential. It was observed that the longitudinal friction potential decreases with increase in both load and speed.

This paper discuss the findings of this work carried out and also on development of generic methodology to measure and estimate the friction potential of tire using wheel force transducer in on-road testing. This methodology can be used for further on-the-field testing and evaluation of tires for research.