Process optimal design in non-isothermal backward extrusion of a titanium alloy by the finite element method

A new approach to process optimal design in non-isothermal, non-steady metal forming is presented. In this approach, an optimal design problem is formulated on the basis of an integrated thermo-mechanical finite element process model so as to treat diverse process parameters, either thermal or mechanical, as the design variables to be optimized, and a derivative based approach is adopted for conducting optimization. Described in detail are the integrated process model, a formulation for process optimal design, and the schemes for the evaluation of design sensitivity, in particular, a scheme for reflecting the effect of remeshing on design sensitivity. The validity of the schemes for the evaluation of design sensitivity is examined by performing a numerical test. Also examined is the integrated process model regarding its capability of predicting defect formation, through comparison with experimental observations. Then, the proposed optimal design technique is applied to process optimization in non-isothermal backward extrusion of a titanium alloy, with emphasis on preventing defect formation.