Biaxial tensile experimental study on the yield loci of steel sheet BH220

On the basis of biaxial tensile experimental system, auto steel sheet BH220 was studied under different loading paths u-sing optimized cruciform specimens. According to the curves of the true stress-logarithmic strain, the exponent of work hardening becomes larger when the load ratio is near to 1:1. Also, the geometry of experimental yield loci was determined based on the equivalent plastic work. The comparison between the experimental data points and the yield loci calculated from several anisotropic yield criteria such as Hill48, Logan-hosford and Barlat-lian shows that Hill48 overestimated the yield stress in all the contours. Among these three yield criteria Logan-hosford gave the best fitness to the experimental data points, especially along the transverse direction.