Convex plastic potentials of fourth and sixth rank for anisotropic materials

Houtte, Paul Van; Bael, Albert Van

doi:10.1016/j.ijplas.2003.11.005

Cited by 44 publications

(28 citation statements)

References 18 publications

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“…Classically, the parameter identification makes use of material data issued from mechanical tests, such as yield stress values and/or r-values from tensile tests, biaxial tests, shear tests, plane strain tests, etc. An alternative method uses a micromechanical model and crystallographic texture data for the identification and has been extensively used for the parameter identification of plastic potentials [12,15,17,34,45]. Both identification techniques have been used in this work, and the impact of the identification procedure on the results of the FE simulations is one of its main objectives.…”

Section: Parameter Identificationmentioning

confidence: 99%

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

Rabahallah¹,

Bouvier²,

Balan³

et al. 2009

Materials Science and Engineering: A

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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.

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Section: Parameter Identificationmentioning

confidence: 99%

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

Rabahallah¹,

Bouvier²,

Balan³

et al. 2009

Materials Science and Engineering: A

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“…Van Houtte et al [3,7,10] describe the plastic anisotropy of textured polycrystalline materials by means of a plastic potential (D) in strain rate space. The potential is identified as the plastic work dissipated per unit volume in function of the macroscopic plastic strain rate D. For rate-insensitive materials, the deviatoric stress tensor S derived from the plastic flow stress can be calculated for a given tensor D as:…”

Section: Strain Rate Spacementioning

confidence: 99%

“…The parameters in these expressions can be either obtained from real mechanical tests [1], or from virtual tests using a multilevel model to obtain the anisotropic response of the material. The latter approach is adopted in previous work of Van Houtte and Van Bael [2,3]. They have used the theory of plastic potentials in strain rate space and stress space [4][5][6][7] in combination with the Taylor theory [8] as multilevel model.…”

Section: Introductionmentioning

confidence: 99%

“…The problem of non-convexity was solved thanks to a new mathematical expression for the plastic potential in strain rate space [3], which is referred to as the "Quantic method". A mathematical criterion could be formulated to ensure the overall convexity of the yield surface, and an iterative algorithm was proposed to slightly modify the fitted parameters in order to satisfy that criterion.…”

Section: Introductionmentioning

confidence: 99%

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The facet method for plastic anisotropy of textured materials

2008

Self Cite

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The Facet method is a new approach to implement the plastic anisotropic behaviour of polycrystalline materials in finite-element models for simulating metal forming processes. It employs analytical expressions of plastic potentials in strain rate space and/or stress space. The parameters in these expressions are obtained by fitting to the predictions of a multilevel model for the plastic deformation of a textured material. The resulting equipotential surfaces in strain rate space and yield loci in stress space are automatically convex. Examples of q-values and uniaxial yield stress variations as obtained with the Facet method in combination with the Taylor theory are shown for three industrial sheet metals. The results are compared to the ones calculated directly from the Taylor theory and those obtained with the Quantic method.

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“…The yield locus size is defined by the chosen isotropic hardening model and its position by the chosen kinematic hardening model. Other teams use micro-macro approaches, where the texture evolution is known and used from time to time, to update the yield locus shape (Van Houtte and Van Bael, 2004). Between the updating steps of the yield locus after a given strain interval (typically after 20% of plastic deformation in Peeters et al (2001)), they rely on a constant yield locus shape that must again be expressed in a specific local frame.…”

Section: Introductionmentioning

confidence: 99%

Rotation of axes for anisotropic metal in FEM simulations

Duchêne

Lelotte

Flores

et al. 2008

International Journal of Plasticity

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For the FE simulations relying on elasto-plastic models based on anisotropic yield locus description, it is important for the simulation accuracy to follow a Cartesian reference frame, where the yield locus is expressed. The classical formulations like the Hill 1948 model keep a constant shape of the yield locus when other texture based yield loci regularly update their shape. However in all these cases, the rotation of the Cartesian reference frame must be known. For simple shear tests performed on steel sheets, experimental displacements provide the actual updated position of initial orthogonal grids. The initial and final texture measurements give information on the average crystals rotation. For Hill constitutive law and texture based models, this paper compares the experimental results with different ways to follow the Cartesian reference frame: the co-rotational method, an original method based on the constant symmetric local velocity gradient and the Mandel spin computed by four different methods.

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Convex plastic potentials of fourth and sixth rank for anisotropic materials

Cited by 44 publications

References 18 publications

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

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

The facet method for plastic anisotropy of textured materials

Rotation of axes for anisotropic metal in FEM simulations

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