High temperature design with cross-ply titanium matrix composites

A modeling technique to predict the high temperature behavior of cross-ply titanium matrix composites (TMCs) subjected to creep and cyclic loading is developed. The material system is a cross-ply SiC-fiber/Ti-6-4-matrix composite. It was found that the constitutive equations of the TMC could be obtained by performing constant strain rate and rapid cycle loading tests in the 0/90 and ±45 orientations at 480°C. A micromechanical analysis is performed to interpret the experimental results, specifically with respect to fiber-matrix debonding and matrix plasticity. Together with a macromechanical analysis, the constitutive equations of the TMC are represented by means of isochronous contours. The constitutive equations are then incorporated in to a finite element analysis. The computational effort of the finite element analysis is reduced by employing the modified shear modulus method. The material model is implemented in the general purpose finite element package ABAQUS as a user material subroutine. The validity of the approach is established by comparing the numerical calculations with experimental results. Some design applications are presented to demonstrate the features of the modeling technique.