Evolution of anisotropy during twisting of cold drawn tubes

On the Rotation of Orthotropic Axes Under Uniaxial Off-Axis Tension in Sheet Metals

“…Kim demonstrated that the answer for the first question is positive [1]. Kim and Yin's [3] experiments corroborate the results of Kim's experiment [1].…”

“…Kim demonstrated that the answer for the first question is positive [1]. Kim and Yin's [3] experiments corroborate the results of Kim's experiment [1]. In the next step, they have provided answers to the second and third questions.…”

“…The re-orientation of orthotropic axes due to the off-axis uniaxial tensile load has a major importance when the rate of this rotation is significant while the system of axes preserved. Kim observed that during the twisting of the cold drawn tubes [1], the orthotropic symmetry is maintained but the orthotropic axes rotate in the twisting direction. Boehler et al, Kim and Yin and Losilla et al have shown that the cold rolled sheet metals under uniaxial off-axes tension loading remain approximately orthotropic but there is a large in-plane re-orientation of the orthotropic symmetric axes [2][3][4].…”

Evolution of yield surface in the 2D and 3D stress spaces

“…Phillips and Das (1985) determined initial and subsequent yield surfaces in the (r hh À r zz À r hz ) space and presented yield loci of the yield ellipsoid cut by various planes parallel to the r hz axis. A different type of experiment performed by Samanta's group (Kim, 1992;Kumar et al, 1991;Mallick et al, 1991) on thin-walled tubes was to independently control the axial load, torsion, and internal pressure to simulate uniaxial stressing of a thin-walled element along a direction making an angle a with the circumferential direction h of the tube (called off-axis tension by Takeda and Mizukami (2008)). The uniaxial yield stress denoted by r u was determined and plotted against the changing a in Fig.…”