Effect of Water Depth and Translational Velocity on Tire Force and Moment Characteristics 2010-01-0770
It is well known that tire force and moment properties are affected by numerous design variables such as tire size, type, compounding, and construction. It is also true that environmental conditions such as rain, snow, or road surface type can alter the cornering capacity of a tire. In this study, specific environmental parameters related to water on the roadway are varied to study the effects on the force and moment properties of modern radial tires. The parameters under study included translational velocity and water depth during standard sweep testing at two different vertical loads.
The force and moment characteristics of seven different tires were tested at the Calspan Tire Research Facility in Buffalo, New York. The slip angle sweep tests were conducted on the Flat Trac tire machine at various belt speeds, normal loads, and water depths. The tires were selected such that there were a variety of different makes, brands, sizes, designs consisting of P-metric and LT (Light Truck), as well as tread designs (i.e. all season and all terrain). The test data was processed and plotted to scientifically analyze tire performance characteristics such as saturated lateral force, cornering stiffness, aligning stiffness, loaded radius, and overturning moment properties. A least squares curve fit as well as a Pacejka model were then evaluated to see if tire force and moment properties on wet surfaces could be predicted from dry surface performance data.
The results of this study show that belt speed, normal load, and water depth do have a significant effect on tire force and moment properties for all tires evaluated. The test data documents numerically how these environmental changes affect the ability of the tires to generate forces and moments. This study also confirms that attempting to simulate tire force and moment properties for conditions of various water depths from dry road force and moment experimental data may not be accurate enough for vehicle dynamics simulations.