Articles

Evolution of anisotropy of sheet metals during plastic deformation

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Abstract

 

Sheet metals generally exhibit a considerable anisotropy due to their crystallographic texture. The mechanical anisotropic characteristics of the sheet metal have a great influence on the shape of the specimen after the deformation. Therefore many successful phenomenological models have been proposed for use in Finite Ele-ment (FE) codes to simulate the anisotropic behavior of a material. The anisotropy is mainly described on the basis of the initial Lankford coefficients and/or yield stresses along the orthotropic (rolling and transverse) and diagonal axes of the sheet metals. The different yield functions make use of different combinations of these constant parameters to represent a 3-dimensional surface (in case of plane stress) determining the transition between elastic and plastic deformation. Generally, the evolution of anisotropy is not considered in the formulation of a constitutive model. Therefore we studied the effects of plastic work on the evolution of anisotropic behavior. The experiments consist of conventional tensile testing of specimens taken at different orientations with respect to the rolling direction. Strain measurements are performed by means of an optical measurement technique. A simple (but powerful) technique for considering distortional anisotropy applicable to any yield criterion is presented. This technique is based on the polynomial definition for instantaneous Lankford coefficient combined with Newton-Raphson iteration. The same approach is applied for evolution of yield stress.

Keywords: Metal characterization, Digital image correlation, Lankford coefficient, Anisotropy, Deep drawing steels

How to Cite:

Safaei, M. & De Waele, W., (2013) “Evolution of anisotropy of sheet metals during plastic deformation”, International Journal of Sustainable Construction and Design 4(1). doi: https://doi.org/10.21825/scad.v4i1.746