Investigation of surface topography evolution of sheet aluminum under pressure and tension

Besides tool parameters and work piece properties, the accuracy of the finite element analysis depends much on contact conditions between the sheet and the tool. To a large extent, the contact conditions are determined by the material properties of the parts in contact as well as the relative motion and the contact pressure between them. A further factor influencing friction is the sheet surface topography which is changing due to tension, contact and sheet deformation. In this paper, the surface topography evolution under pressure and under tension is presented and discussed. Therefore, basic experiments were done. In the experiments, the influence of different parameters like tension and contact pressure is determined. To analyze the surface topography evolution, pre-defined spots on the samples were traced during the experiments. The changes in the surface topography before and after forming were analyzed by means of roughness measurement. The intention is to get a correlation between flattening or roughness evolution and the parameters of the deformation. This correlation can be used to improve existing friction models used in the FE analysis