Finite Element Analysis of Freely Rotating Tires

Abstract

Abstract Axisymmetric analysis of an inflated tire rotating with constant angular speed can be used to simulate two loading conditions of a tire during its service life: (1) a freely rotating tire on an automobile that is stuck in snow or mud and (2) the top region of a rolling loaded tire, where footprint loading has little influence on the distribution of its stresses and strains. The equations of motion for a freely rotating deformable body with constant angular speed have been derived and implemented into a finite element code developed in-house. The rotation of a thin disk was used to check the validity of the implemented formulation and coding. Excellent agreement between the numerical and the analytical results was obtained. A cast tire, a radial automobile tire, and a radial truck tire, were then analyzed by the new finite element procedure. The tires were inflated and rotated at speeds up to 241 km/h (150 mph). The elastomers in these tires were simulated by incompressible elements for which the nonlinear mechanical properties were described by the Mooney-Rivlin model. Each ply was simulated by its equivalent orthotropic material model. The finite element predictions agreed well with the available experimental measurements. Significant changes in interply shear strain at the belt edge, the bead load, and the crown cord loads of plies were observed in the finite element analysis. These phenomena suggest three possible failure modes in freely rotating tires, i.e. belt edge separation, bead breakage, and belt failure at crown region.