Modelling the superplastic behaviour of the Ti6Al4V-ELI by means of a numerical/experimental approach

In the present work, the superplastic behaviour of a Ti6Al4V-ELI titanium alloy at the temperature of 850 °C is assessed combining experiments and numerical simulations managed by a genetic algorithm-based optimization loop. The experiments consisted of free inflation tests characterized by either a constant gas pressure or several pressure jumps during the same test. Dome height evolutions from tests setting a constant gas pressure were used to evaluate the parameters of the classical strain rate power law material model using an analytical approach from literature. An alternative set of material constants was then evaluated using the inverse analysis based on a genetic algorithm coupled to dome height data from jump pressure tests. Numerical results, in terms of thickness distribution and dome height evolution, obtained from simulations implementing material constants from the inverse analysis fit experimental data in a wider range of strain rates than the ones implementing material constants from the analytical approach.