Process Modeling of Freeform Incremental Forming Using LS-DYNA

Incremental Sheet Forming (ISF) is a manufacturing process for sheet metal prototyping where the blank is incrementally deformed into a desired shape by one or more stylus tools traveling along a prescribed path. Conventional ISF can be categorized into two types, Single-Point Incremental Forming (SPIF) where the sheet metal is formed from one side by a single stylus tool; and Double-Point Incremental Forming (DPIF) where a die positioned underneath a stylus tool pushes the sheet metal to wrap around the die. More recently a Freeform Incremental Forming (FIF) is developed at Ford Motor Company where two stylus tools synchronized in motion and deform the sheet metal from opposite sides as they are traveling to form a product shape. The new technology provides significant advantages for sheet metal fabrication process in terms of cost and flexibility because forming dies are completely eliminated and complex geometries can be formed. However the uniqueness of the process also brings significant challenges to its process design. This paper presents new capabilities developed in LS-DYNA for simulating Freeform Incremental Forming (FIF). The rigid stylus tools can move arbitrarily in both translational and rotational Degrees-of-Freedom (DOF). Challenges for numerical simulations and their modeling techniques are addressed in the paper. Numerical and experimental examples of Freeform Incremental forming processes are presented. It is demonstrated that the simulation results correlates very well with laboratory measurements.