A Model Analysis of Tire Behavior Under Vertical Loading and Straight-Line Free Rolling

Abstract

Abstract A structural analog, consisting of a flexible circular ring under tension with a nest of radially arranged linear springs and dampers, is developed as a pneumatic tire model. The model is concerned with the prediction of the tire's vertical load-deflection characteristics and its free rolling resistance. The mathematical formulation of the boundary of the model's region of contact with a smooth hard surface is based on approximations made using the theory of a tensioned string supported by an elastic foundation. Forces developed within the contact region are computed from geometrical considerations. The model's ring tension and radial foundation stiffnesses, as related to the tire's inflation pressure, are obtained experimentally by performing contact patch length measurements and static point-load tests on the specific tire modeled. Further, by prescribing a loss factor in the radial dampers, the model's free rolling resistance characteristics may be computed. Experimental verification conducted on a radial tire shows general agreement between the predicted and experimental vertical load-deflection characteristics for the normal working range of inflation pressure, deflection, and interacting surface curvature. The predicted rolling resistance characteristics are also found to be in good accord with experimental measurements.