Force-based failure criterion in incremental sheet forming

In incremental sheet forming, a hemispherical tool deforms a sheet moving along a predefined path. The process, useful for making prototypes or small series, is characterized by high flexibility and development times and costs reduction. The part feasibility is strongly influenced by the adopted tool path and, in particular, tool path corrections are requested to obtain the final geometry and to prevent the sheet rupture. To save time and costs, sheet failure criteria are therefore essential. In this paper, a real time force-based sheet rupture criterion is presented and tested on steel, aluminum, and titanium alloys. In particular, it will be shown that the sheet rupture can be related with the tangential forming force, the geometry of the component to be realized, and the sheet material characteristics.