Finite element modelling of damage in superplastic forming of a titanium alloy

Abstract

This paper describes the application of a continuum damage mechanics methodology to the prediction of failure during superplastic forming of Ti-6Al-4V. A power law constitutive relationship is employed within a geometrically non-linear finite element model of the forming process and a user subroutine is developed to implement the damage mechanics approach. The damage constants are identified from uniaxial rupture strains from constant strain-rate tests. The multiaxial implementation is successfully used to predict damage evolution during forming of a truncated cone and is shown to predict results consistent with the experimental results from forming trials.