engleski

An analysis of non-associated plasticity formulations in deep drawing simulations

In this paper, a recently developed finite element formulation based on the non-associated plasticity is applied to sheet metal forming simulations. A short review of the analyzed non-associated constitutive formulation and the stress integration procedure for its implementation into finite element codes are presented. Simulations of a square cup drawing for mild steel and a circular cup drawing for aluminum alloy Al2008-T4 are performed with associated and non-associated plasticity formulations based on the Hill (1948) stress functions. In order to describe the strength differential effect observed for Al2008-T4, an investigation is carried out with a non-associated formulation based on an orthotropic/asymmetric yield criterion. The influence of the material model characterization on the predictions of uniaxial material properties and cup drawing is analyzed. The predicted cup profiles and thickness strain distributions are compared with experimental data, and the acceptability of the used stress functions under associated or non-associated flow rule is assessed.

planar anisotropy ; non-associated flow rule ; orthotropic/asymmetric yield function ; finite element method ; cup drawing

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