부산대학교 도서관

A commercial AZ31 magnesium alloy sheet has been tested under proportional biaxial tensile loading using crucifonn specimens. In order to quantitatively determine the plastic deformation behavior of the test material, the contours of plastic work and the directions of plastic strain rates were precisely measured over a range of equivalent plastic strain, 0.001 ≤ ε^P_0 ≤ 0.008. The measured work contours and the directions of plastic strain rates have been compared with those predicted using some conventional yield functions. The r-values for RD, 45° to RD and ID have been measured using strain gauges after complete unloading at specific levels of equivalent plastic strain. The yield loci of the material were recalculated corresponding to the r-values measured at the same level of plastic strain. It was found that evaluating the r-values corresponding to the same level of plastic strain significantly affects the shape of the calculated yield locus while Hill'48 and the Yld2000-2d yield criteria are used.