Title: Calibration of anisotropic yield criteria with crystal plasticity data
Authors: Gawad, Jerzy
Comsa, Dan Sorin
Van Bael, Albert
Banabic, Dorel
Eyckens, Philip
Samaey, Giovanni
Roose, Dirk
Van Houtte, Paul #
Issue Date: Oct-2012
Conference: Multiscale Materials Modelling (MMM) edition:6 location:Singapore date:15 - 19 October 2012
Article number: G4-4
Abstract: Direct coupling of crystal plasticity models (CP) with Finite Element formulations still has limited applicability to macroscopic forming processes due to its prohibitive computational cost. A convenient alternative could be to approximate the outputs of a CP by a relatively simple formula, describing a property of interest, e.g. plastic anisotropy. In this paper we assume that plastic anisotropy of a polycrystalline alloy is predominantly determined by its crystallographic texture. Thus, a CP model, such as FC Taylor or ALAMEL, would be able to provide complete data for identification of yield loci. We employ this concept to calibrate two fundamentally different macroscopic formulas describing plastic anisotropy: a plane-stress yield stress criterion BBC2008 [1] and a generally applicable plastic potential Facet [2]. Mathematical framework of the BBC2008 is sufficiently flexible to allow 8, 16 or 32 parameters. To determine these, conforming number of data points is needed, each one consisting of an r-value in given uniaxial loading direction and the corresponding stress. This involves difficulties in data acquisition, because both considered CP models are strain rate driven. We present how to overcome this limitation by means of an iterative search procedure. Conversely, the Facet potential function can be completely determined by direct calls to the strain rate driven CP codes. A case study on AA1100 aluminum alloy is presented. We investigate quality of approximations by the BBC208 and the Facet. It is found that both formulations can capture complex anisotropic “eight-earing” behavior of the tested material. We also verify the plastic anisotropy derived from the texture by results of mechanical tests, providing instantaneous and cumulative r-values.

[1] D. Comsa, D. Banabic, Plane-stress yield criterion for highly-anisotropic sheet metals, in: Numisheet 2008, Interlaken, 2008, pp. 43-48.

[2] P. Van Houtte, S.K. Yerra, A. Van Bael, Int. J. Plast. 25 (2009) pp. 332-360.
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Numerical Analysis and Applied Mathematics Section
Department of Materials Engineering - miscellaneous
Structural Composites and Alloys, Integrity and Nondestructive Testing
Technologiecluster Materialentechnologie
Materials Technology TC, Technology Campus Diepenbeek
# (joint) last author

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