Numerical simulation of sheet metal forming using anisotropic strain-rate potentials

Abstract

For numerical simulation of sheet metal forming, more and more advanced phenomenological functions are used to model the anisotropic yielding. The latter can be described by an adjustment of the coefficients of the yield function or the strain rate potential to the polycrystalline yield surface determined using crystal plasticity and X-ray measurements. Several strain rate potentials were examined by the present authors and compared in order to analyse their ability to model the anisotropic behaviour of materials using the methods described above to determine the material parameters. Following that, a specific elastic-plastic time integration scheme was developed and the strain rate potentials were implemented in the FE code. Comparison of the previously investigated potentials is continued in this paper in terms of numerical predictions of cup drawing, for different bcc and fcc materials. The identification procedure is shown to have an important impact on the accuracy of the FE predictions.

Earings prediction by a finite strain multiplicative formulation for anisotropic elastoplastic materials

“…In the FE simulation a quarter section of the cup was analyzed owing to the orthotropic material symmetry. In this paper two configurations are considered: cup drawing of the aluminium alloy Al-5 wt.% Mg, as described in [27], and drawing of AA2008 aluminium alloy sheets, as given in [37].…”

“…The tool dimensions and the process parameters are given in [37] and are summarized in Table 3. The Hill's parameters of the model have been identified based on the experimental r-value distribution depicted in Fig.…”

“…www.gamm-mitteilungen.org The isotropic hardening material parameters are chosen according to [37]. The material parameters read: μ = 26315.…”

“…The material parameters read: μ = 26315. Distribution of r-value of AA2008 alloy; experimental data from [37] Fig . 8 shows the deformed geometry of a fully-drawn cup with the corresponding earing profile.…”

“…The finite element formulation and implementation of Barlat's yield functions together with prediction of earings is discussed in a number of works of Yoon and coworkers ( [25], [26], [27], [28], [29] [30]). Further recent papers discussing the modelling and simulation of earings in cup drawing include [31], [32], [33], [34], [35], [36] and [37].…”