Controlling Product Properties by Compressive Stress-Superposed Incremental Forming

Forming-induced residual stresses can be used to increase the fatigue strength of formed components. By adjusting the process parameters of the incremental sheet metal forming process (ISF), the forming mechanisms can be adjusted and thus the resulting residual stress can be targetedly set, to meet specific component requirements. Within the scope of this work, experimental results show that superposed compressive stresses using a flexible polymer die during ISF, near-to-surface compressive residual stresses can be induced on both sides of aluminum alloy 5083 truncated cones. The resulting residual stress state is measured by means of X-ray diffraction (XRD). In addition, the amount of near-to-surface residual stress can be adjusted by varying the degree of hardness of the elastomeric die material. These findings can be used to set tailored properties of formed components by forming-induced residual stresses, to extend the operating time of the component until failure.