Calculation of the Structural Stiffness of Run-flat and Regular Tires by considering Strain Energy

The vertical stiffness of a tire is defined by the ratio of the vertical force to the deflection; it can be expressed as the combination of the structural stiffness and air stiffness. However, the calculation of the structural stiffness alone is challengeable, and therefore this paper presents a new methodology for extracting the structural stiffness from the strain energy of the regular and run-flat tires. In order to verify our proposed method, the applied force-deflection relationship was compared with the calculated force-deflection relationship using the proposed energy method at zero air pressure. Further, the structural stiffness of the inflated regular and run-flat tires was calculated. In addition, we obtained the structural stiffness of the tire components to investigate the effect of each component on the overall structural stiffness of both tires. Finally, we analyzed the vertical and structural stiffness of the run-flat tire when the inflation pressure and the elastic modulus of the components were varied.