Inflation and contact predictions of composite tire shell carcass

A passenger car tire is analyzed by treating it as a laminated, anisotropic thin shell that deforms according to the classical Love hypothesis. The tire is modeled using a high-order, doubly curved, quadrilateral thin-shell finite element. The element employs variable-order polynomials for the definition of geometry of the structure and, thus, provides an accurate modeling of the initial profile of the tire, which significantly affects the response of the tire. The material properties of the cord-rubber system forming the tire carcass are assumed as piecewise homogeneous and are obtained by employing the fundamentals of composite material theory. The effect of geometric nonlinearity is included in the formulation to account for stiffening or weakening of the carcass due to deformation. A detailed investigation of deformation and stresses in the tire due to inflation is first made using a load increment algorithm. The inflated tire is next brought into static contact against a rigid surface in a displacement increment procedure to study 1) the displaced profile of the tire in contact, 2) the redistribution of resultant forces and moments in the tire due to contact, 3) the force required to bring the tire in contact, and 4) the footprint of the tire. The developments discussed in this paper may be applied to the study of deformation mechanics in aircraft tires.