Plane Strain Deep Drawing: Finite Element Modeling and Measurements 910774
Plane strain, deep drawing experiments were performed to obtain precise strain information for comparison with membrane section-analysis finite element modeling (FEM) results obtained using a FEM program, SHEET-S. Strains on both outer and inner specimen surfaces and draw-in displacements were carefully measured at various punch heights, for varying blank holder loads, and for three square-punch edge radii representing r/t ratio (radius/sheet thickness) of 3, 6, and 9. SHEET-S, a rigid-viscoplastic section analysis finite element program, for plane strain stretching and deep drawing with general tooling shape, has developed and tested by plane strain deep drawing of strips. Simulations and experiments are in good agreement for the large r/t ratios, but deteriorate for r/t ≈ 3, especially for low blank holder loads. Bending and unbending at these locations appear to dominate the deformation modes, causing significant differences from the strains predicted by the membrane FEM. A simple bending modification of membrane FEM results was necessary and introduced through t/2R correction, which gave good prediction of peak surface strains in cases of r/t ratio large than 6.