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Comparison of simple and full approach for non- associated formulation based on Karafillis- Boyce stress function

In the present paper an orthotropic elasto- plastic constitutive formulation for sheet metals is analyzed. The formulation is based on the non-associated flow rule, the isotropic hardening concept and utilizes orthotropic four parametric Karafillis-Boyce stress function as yield function/plastic potential. In defining the evolution equation for the equivalent plastic strain, as hardening parameter, two approaches are considered. By full approach, the equivalent plastic strain increment is proportional to the ratio of plastic potential and yield function where the plastic multiplier is proportionality factor. By simple approach, the equivalent plastic strain increment corresponds to the plastic multiplier. For considered constitutive descriptions, algorithmic formulations, based on the implicit return mapping, are developed and analyzed in predicting simple deformation tests and the cylindrical cup deep drawing process for AA5754-H22 sheet sample. Influence of the equivalent plastic strain evolution equation on the model predictions is assessed.

equivalent plastic strain ; non-associated flow rule ; Karafillis-Boyce stress function ; cylindrical cup deep drawing ; sheet metals

IEEE CatalogNumber: CFP19F09-USB