Nonlinear finite element analysis for composite structures of axisymmetric geometry and loading

A linear strain, axisymmetric, triangular finite element is formulated for the modeling of materials which are generally orthotropic in the plane of the fibers and loaded axisymmetrically. The fibers may be oriented in planes other than the symmetric plane.This necessitates the use of three displacement degrees of freedom at each node.The element is also formulated to include geometric nonlinearity to take into account any stiffening or weakening of the structure due to deformation.The element is programmed into a finite element code, which is validated using a well-known isotropic nonlinear problem. It shows very good agreement with the results of other programs.The unique application of the element is shown in the analysis of a pneumatic tire.