ON THE ROTATION OF ORTHOTROPIC AXES UNDER UNIAXIAL OFF-AXIS TENSION IN SHEET METALS

Abstract

Experimental investigations show that when orthotropic sheet metals are subjected to off-axis uniaxial tension, a re-orientation of the axes occurs, while orthotropic symmetries are preserved. In this paper this phenomenon is investigated and formulated based on the following assumptions: the principal direction of the plastic strain increment is the same as the direction of the orthotropic axes of the sheet metal and Lankford’s number remains unchanged. A simple and applicable method is presented which relate the rate of change of orthotropic axes rotation under uniaxial off-axis tension with plastic strain increment. Also, a new and simple method is developed to obtain the direction of the orthotropic axes rotation under uniaxial off-axis tension. It is shown that the proposed methods can successfully be used to obtain the magnitude and direction of the rotation of the orthotropic axes and the results show good agreement with the experimental.

DOI: http://dx.doi.org/10.5755/j01.mech.19.3.2597