A Phenomenological Concept to Predict Formability in Stretch-Bending Forming Operations

In sheet forming, stretch-bending deformation, (i.e. combined deformation of simultaneous stretching and bending when sheet material is stretched over a defined tool radius), is known to enhance material formability. In order to use this forming potential of sheet material, current research put its emphasis on the experimental characterization of the formability of sheet material, subjected to stretch-bending deformation and on a more reliable formability prediction in complex shaped parts. Nevertheless, significant limitations exist in the current available experimental setups for the characterization of the stretch-bending formability of sheet material. Furthermore, the predictive quality of existing formability prediction models is not sufficient to meet current industrial requirements. In this work results of an experimental characterization of influences on stretch-bending formability using existing and newly developed stretch-bending test setups are presented and a phenomenological concept that uses the experimental results to predict formability in Finite-Element simulations of complex shaped parts involving stretch-bending deformation is proposed.