Development of a system for modeling the stretch-forming of automotive panels, using an elastic-plastic, membrane-type finite-element formulation which includes a treatment of friction between punch and the forming sheet. Application of this system to model the forming of the 1984 Camaro lift window outer. A mathematical representation of the punch and die are constructed using cubic B-splines to construct a spline-blended free form surface. A random array of FEM nodes is imposed on the sheet, using the Delaunay triangulation. A simple Hollomon power law is used to represent strain hardening. A coefficient of friction of 0.15 is assumed. Strains above the forming limit are found at the corners of the sheet, indicating failure. This is consistent with data on the actual part at the die prototype stage, where failure by tearing in fact occurred at the corners. In actual production some draw-in of metal had to be allowed.
Finite element modeling of a stretch-formed part
FEM-Modellmethode fuer streckgezogene Werkstuecke
1985
14 Seiten, 9 Bilder, 14 Quellen
Conference paper
English
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