Simulation of residual stresses and their impact on geometrical accuracy in incremental sheet metal forming

Abstract

AbstractThe current study presents the influence of the process parameters on residual stresses and geometrical accuracy in single point incremental forming (SPIF). In SPIF, a sheet metal is formed by the continuous localized deformation of a hemispherical tool. In this regard, pyramidal parts from an aluminum alloy are incrementally formed by varying the process parameters. Small strips are cut from the side walls of these pyramids and the resulting curvature of the strips is measured and compared. The bore‐hole‐drilling method is used to measure the residual stress state. Further, two different numerical models employing isotropic and mixed hardening rules are calibrated based on the residual stresses. The model with mixed hardening predicts better results. This validated numerical model is used to simulate the geometric deviation upon trimming. The resulting curvature of the trimmed strips from the numerical simulations is compared to the curvature of the experimental strips. A good agreement is found. Hence, the developed model can be used to accurately simulate the residual stresses and in turn the trimmed geometry after SPIF.