Experimental and Numerical Investigation of Forming Limit Diagram of CP-Ti/St12 Bimetal in the Incremental Forming Process

Abstract

Single point incremental forming is a method which has the capability of sheet forming by a semispherical tool without the necessity of using specific die. In the present study, Forming Limit Diagrams (FLD) of explosively-welded CP-Ti/St12 bimetal sheet have been evaluated. The effects of process parameters and layer arrangements (St-Ti and Ti-St) were investigated on the FLD and thickness variations. For this purpose, standard circular pattern was carved on the sheets. The changes of strain at the carved pattern and thickness distribution were measured using Video Measuring Machine (VMM). The diagrams of FLD and thickness distribution were achieved using the obtained points and related relationships. Also, the single point incremental forming process was simulated using ABAQUS finite element software to evaluate rupture moment and thickness distribution. According to the experimental results, the sheet formability increased to 30% in the layer arrangement of Ti-St in comparison to St-Ti and the error between finite element and experimental result was about 15%. The effects of layer arrangement, vertical step down, and spindle speed on thickness distribution were about 45, 17, and 12%, respectively.