Rotation of Orthotropy Axes of Steel Sheets by Tensile Elongation

인장변형에 의한 강판의 직교이방성 대칭축의 회전

A series of tensile tests have been performed to investigate the hardening behavior of rolled steel sheets. Tensile tests consist of three stages. At the 1st stage, full size tensile specimens were prestrained in the direction of rolling, then mid-sized tensile specimens were cut from the gauge sections of the full size specimens at angles to the rolling direction. At the 2nd stage, mid-sized specimens were prestrained by predetermined magnitudes of strains and miniature tensile specimens were prepared from each of the mid-sized specimens at every 10 degrees. At the final stage, from tests on miniature tensile specimens the hardening behavior of the prestrained sheets has been investigated. According to the experimental results, orthotropic symmetry is reserved during tensile elongation, and one of the orthotropy axes is continuously rotated to specimen axis. Existing theories seem to fail to explain the rotation of orthotropy axis. A new phenomenological model is proposed to explain the strain induced rotation of orthotropy axes.