Numerical study on spoke ovality effect on airless tire transverse stiffness

Regular non pneumatic tire heavily relies on compressed air and that cause it to be fragile in harsh and rough routes. Non pneumatic tire innovation is introduced to resolve this issue. Non pneumatic tire structure consists of two internal and external crusts which are connected with spoke shaped structure. Geometrical diversity in shape of spokes used in non-pneumatic tires cause a wide range of mechanical behaviors and stiffness-endurance properties. In this paper, a specific class of airless tires which employ rounded elements as spokes geometry is selected to be studied. The shape of spokes could be varied by changing their ovality from perfect circular to relatively extended ellipse. The ovality of spokes could induce complex deformations and instabilities which affects the transverse behavior of tires. Regarding the planar symmetry of geometries, two dimensional models are developed to investigate the nonlinear behavior of tire transverse deformations. The results of numerical simulations revealed that by changing the level of ovality, load-deflection curves could be altered in such a way that suitability of every geometry for different applications could be determined based on the slope of mentioned curves.