Inverse analysis approach for determining the superplastic behaviour of the Titanium alloy Ti6Al4V-ELI

A. Piccininni, P. Guglielmi, D. Sorgente, G. Palumbo, L. Tricarico (Politecnico di Bari)

CHALLENGE - Superplastic Forming (SPF) is considered one of the most suitable innovative solutions when highly complex components need to be manufactured. A Finite Element (FE) approach is always necessary if components characterized by optimal thickness distributions are requested. The characterization of the superplastic behaviour of the Titanium (Ti) alloy Ti6Al4V-ELI (Extra Low Interstitial), largely adopted for biomedical applications, was carried out by means of free-inflation tests: both tests at a constant pressure and alternatively varying the gas pressure between two levels (JP test) were performed. 

SOLUTIONS - The evaluation of the material constants was demanded to an inverse analysis approach aimed at minimizing the difference between the experimental dome height curve acquired during the JP tests and the correspondent numerical one calculated using the FE model. ​ The inverse analysis was carried out adopting a multi-objective genetic algorithm MOGA-II employed in the modeFRONTIER workflow.

BENEFITS - The genetic algorithm gave back the optimal value of the material constants able to minimize the error between experimental and numerical data (i.e. the evolution of the dome height according to time) acquired during the tests. ​