Experimental and FEM analysis for metal foam bending

This work deals with the formability of metal foams. In particular, it is focused on air bending along straight lines of aluminum foam sandwich panels. A universal testing machine was employed for this purpose and an experimental device for a bending process was set up to collect data about the deformed geometry and about load-displacement data. Several tests were carried out by varying die geometry (punch radius, span, corner radius). The adopted sandwich panels were composed by a foam core of AlMg3Si6 (closed cell) and a cover sheet of AlSi1MgMn (AA6082); both bonded and foamed sandwich panels were employed. Basing on experimental results, a numerical model of the same process was developed by using a commercial FEM code (Deform 2D). Material definition, especially foam compressibility, resulted to be a critical aspect of the model. This problem was overcome by using a compressible (porous) material model. The onset of foam instability was simulated using a damage model based on the foam density parameter. Finally, a comparison between simulative and experimental results allowed to validate the predictive ability of the model. Another load condition, namely upset test between flat parallel dies, allowed a further comparison between FE model and experiment.