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Title: Consistent Parameters for Plastic Anisotropy of Sheet Metal (Part 2- Plane-strain and Compression Tests)

Abstract

To include the case of deep-drawing (without blank-holder), states of combined tensile and compressive stress have to be considered whereby it is necessary to define two more anisotropy parameters. They are called 'tensile-compressive anisotropy' in rolling and transverse direction. Finally, a new consistent system of 'true' anisotropy parameters is presented. They are defined as the difference between the experimentally determined anisotropy parameters and the values which would be obtained in case of isotropy. They all are zero for isotropic materials.

Authors:
;  [1];  [2];  [3]
  1. Institut fuer Statik und Dynamik der Luft -und Raumfahrtkonstruktionen, Universitaet Stuttgart, Pfaffenwaldring 27, D-70569 (Germany)
  2. Institut fuer Umformtechnik, Universitaet Stuttgart, Holzgartenstr. 17, D-70174 Stuttgart (Germany)
  3. Technical University of Cluj-Napoca, C. Daicoviciu 15, 400020 Cluj-Napoca (Romania)
Publication Date:
OSTI Identifier:
21057038
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 907; Journal Issue: 1; Conference: 10. ESAFORM conference on material forming, Zaragoza (Spain), 18-20 Apr 2007; Other Information: DOI: 10.1063/1.2729543; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; ANISOTROPY; COMPRESSION; DRAWING; ISOTROPY; METALS; PLASTICITY; ROLLING; SHEETS; STRAINS; STRESSES; TESTING

Citation Formats

Poehlandt, K., Schoeck, J., Lange, K., and Banabic, D.. Consistent Parameters for Plastic Anisotropy of Sheet Metal (Part 2- Plane-strain and Compression Tests). United States: N. p., 2007. Web. doi:10.1063/1.2729543.
Poehlandt, K., Schoeck, J., Lange, K., & Banabic, D.. Consistent Parameters for Plastic Anisotropy of Sheet Metal (Part 2- Plane-strain and Compression Tests). United States. doi:10.1063/1.2729543.
Poehlandt, K., Schoeck, J., Lange, K., and Banabic, D.. Sat . "Consistent Parameters for Plastic Anisotropy of Sheet Metal (Part 2- Plane-strain and Compression Tests)". United States. doi:10.1063/1.2729543.
@article{osti_21057038,
title = {Consistent Parameters for Plastic Anisotropy of Sheet Metal (Part 2- Plane-strain and Compression Tests)},
author = {Poehlandt, K. and Schoeck, J. and Lange, K. and Banabic, D.},
abstractNote = {To include the case of deep-drawing (without blank-holder), states of combined tensile and compressive stress have to be considered whereby it is necessary to define two more anisotropy parameters. They are called 'tensile-compressive anisotropy' in rolling and transverse direction. Finally, a new consistent system of 'true' anisotropy parameters is presented. They are defined as the difference between the experimentally determined anisotropy parameters and the values which would be obtained in case of isotropy. They all are zero for isotropic materials.},
doi = {10.1063/1.2729543},
journal = {AIP Conference Proceedings},
number = 1,
volume = 907,
place = {United States},
year = {Sat Apr 07 00:00:00 EDT 2007},
month = {Sat Apr 07 00:00:00 EDT 2007}
}
  • The anisotropy parameters for sheet metal used hitherto are mainly determined by uniaxial tensile tests. Such tests, however, do not give sufficient information about the yield locus and the forming behaviour in that range where the two principal tensile stresses are of similar magnitude like in stretch forming. The same applies for combined tensile and compressive stress like in deep-drawing. To fill these gaps, new parameters are defined. Their experimental determination is briefly discussed.The 'equibiaxial yield stress' and 'equibiaxial anisotropy' which refer to equibiaxial tensile stress can be determined by cross tensile tests. However, these require a special apparatus. Alternativelymore » experiments for obtaining plane strain can be applied for determining the equibiaxial parameters indirectly. This is possible using conventional tensile testing machines. In this case also anisotropy parameters for plane-strain deformation, the 'semibiaxial anisotropy' in rolling and transverse direction, can be determined.« less
  • The plastic anisotropy in transverse compression (i.e., the direction of compression, x-axis is perpendicular to the growth direction, z-axis of the specimen) of a directionally-solidified nickel-base superalloy of Hf-modified Mar-M200 composition was studied at 1149 and 1216/sup 0/C. The lateral strain ratio depsilon/sub zz//d epsilon/sub yy/ was found to be in the range of 1.6 to 3.0 and the yield strengths were higher than those of monocrystals yielded along <001>. These data were compared with those predicted from the Hosford-Backofen texture analysis for a model DS structure in which all the columnar grains are parallel to <001> and randomly rotatedmore » about this direction. It was shown that the relatively low plastic anisotropy observed experimentally can be explained, by means of the texture analysis, in terms of the scattering in the growth directions of the columnar grains and the nonrandom rotations of the grains about these directions. The relative yield strengths of monocrystals in plane-strain compression in which the direction of elongatiion is parallel to <001> have been analyzed using Bishop-Hill plasticity analysis which shows that the Taylor factor M is equal to ..sqrt..6, independent of orientation of the compression axis. The theoretical result was experimentally verified, using low-carbon Mar-M200 monocrystals tested under plane-strain condition at 1093/sup 0/C. The experimental results are in good agreement with those of the theoretical analysis.« less
  • A simple way of making plane-strain tension tests on sheet specimens has been developed. This method was used to test sheets of aluminum alloy 2008 T4 and the results were analyzed in terms of a high exponent yield criterion and isotropic hardening. Experimentally measured forces agreed with those calculated from strain measurements using uniaxial tension test curves.
  • Intrinsic, in-plane anisotropy of electrical resistivity was studied on mechanically detwinned single crystals of SrFe{sub 2}As{sub 2} above and below the temperature of the coupled structural/magnetic transition, T{sub TO}. Resistivity is smaller for electrical current flow along the orthorhombic a{sub o} direction (direction of antiferromagnetically alternating magnetic moments) and is larger for transport along the b{sub o} direction (direction of ferromagnetic chains), which is similar to CaFe{sub 2}As{sub 2} and BaFe{sub 2}As{sub 2} compounds. A strongly first-order structural transition in SrFe{sub 2}As{sub 2} was confirmed by high-energy x-ray measurements, with the transition temperature and character unaffected by moderate strain. Formore » small strain levels, which are just sufficient to detwin the sample, we find a negligible effect on the resistivity above T{sub TO}. With the increase of strain, the resistivity anisotropy starts to develop above T{sub TO}, clearly showing the relation of anisotropy to an anomalously strong response to strain. Our study suggests that electronic nematicity cannot be observed in the FeAs-based compounds in which the structural transition is strongly first order.« less
  • Compression tests of single crystals are analyzed with respect to shear due to the friction at the loaded ends. This simple approach permits an explanation of the features associated with prism plane slip in sapphire ({alpha}-Al{sub 2}O{sub 3}), i.e., the shape changes of the specimens and the curvature of the glide planes.