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Pneumatic Tire Performance on Ice
Kishore Bhoopalam, Anudeep
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The evolution of vehicle safety systems, from the earliest brakes to today's accident avoidance systems, has led vehicles to have very high passenger safety. Driving on ice, though, still happens to be one of the driving conditions of low safety. A multitude of factors were identified by various studies to contribute to the complex frictional mechanism at the tire-ice interface. The tire is only force transmitting element of the vehicle, to the surface. Thus it is very essential to have in depth understanding of the contact phenomena at the tire-ice interface, to improve vehicle safety on icy roads. This study has led to understanding of the contact phenomena at the tire-ice contact through experimental studies and a semi-empirical based tire-ice contact model. Experimental studies included both indoor testing and outdoor testing, indoor testing was conducted using the Terramechanics Rig at the Advanced Vehicle Dynamics in Virginia Tech and field tests were conducted at the Keweenaw Research Center in Michigan Tech. The simulation results of the tire-ice model were validated against the findings of the indoor test program. The P225/60R16 97S Standard Reference Test Tire was the candidate tire for this study. The effects of operational parameters, were studied when in driving traction by comparison of the friction - slip ratio curves. The two tests procedures were performed to understand how each test method influences the test results. A comparison of the laboratory and field test method are also presented, with reasons for the differences in the measured values presented. The experimental study also led to development of a modular structured tire-ice model (TIM). The model computes the temperature rise in the contact patch based on the pressure distribution in the contact patch, thermal properties of the tread compound and of the ice surface. The contact patch is then classified into wet and dry regions based on the ice surface temperature and temperature rise simulations. The principle of thermal balance is then applied to compute the friction level in the contact patch. The tire-ice contact model is validated for two parameters: temperature rise and friction levels. Temperature rise from simulations are validated against temperature measurements at the leading and trailing edge of the contact patch. Friction levels at different conditions of load, inflation pressure, and ice temperatures have been simulated using the tire-ice contact model and compared to the experimental findings.
- Doctoral Dissertations