A non-invasive node-based form finding approach with discretization-independent target configuration

Abstract

Form finding is used to optimize the shape of a semi-finished product, i.e. the material configuration in a forming process. The geometry of the semi-finished product is adapted so that the computed spatial configuration corresponds to a prescribed target spatial configuration. Differences between these two configurations are iteratively minimized. The algorithm works non-invasively, thus there is a strict separation between the form update and the finite element (FE) forming simulation. This separation allows the use of arbitrary commercial FE-solvers. In particular, there is no need for a modification of the FE forming simulation, only the material configuration is iteratively updated. A new method is introduced to calculate the difference between the target and the computed spatial configuration. Thereby the target mesh is separated from the mesh for the FE forming simulation, which enables a more accurate and independent representation of the target configuration. In addition, the possibility of taking into account manufacturing constraints in the optimization process is presented. The procedure is illustrated for the example of the first stage of a novel two-stage sheet-bulk metal forming process.

Development of a numerical compensation framework for geometrical deviations in bulk metal forming exploiting a surrogate model and computed compatible stresses

“…Lu [23] investigated airfoil blades obtained by net-shape forging and employed Bspline surface approximation. Landkammer developed an inverse form finding method [24] and employed a shape optimisation approach [25], while Caspari [26] focused on node recognition strategies between different configurations. A fully geometry-based compensation rule was developed by Hartmann and Eder [27], who succeeded in performing the compensation on a set of user-defined surface points through shape morphing of the nominal geometry [28].…”