せん断降伏応力が曲げ加工性に及ぼす影響

抄録

In this study, we investigated the effect of shear yield stress on bendability. We used three types of copper alloy sheet for automotive terminals as test samples and conducted 180 ^o bending, uniaxial tensile, and simple shear tests. The simple shear test was set in the through-thickness direction, and strain was measured by digital image correlation (DIC). All the test samples were wrinkled in the bending test, and some of the materials were cracked. These wrinkles and cracks were caused by shear bands. The ratio of the shear component to the normal component of the yield surface was lower than 0.58(1⁄√3) for all samples, indicating that the shear component is smaller than those of isotropic materials. The ratio of the material in which the bending crack was observed was especially low(0.39). The yield stresses obtained in this study were reflected in Hill’s quadratic function, and elastoplastic analysis by the finite element method was carried out to reproduce the formation of shear bands and the bending wrinkles caused by them.