Anisotropic hardening of MS1180 steel plate: Experimental and analytical modeling Anisotrope Härtung von Stahlblechen aus MS1180: Experimentelle und analytische Modellierung

This work is carried out to investigate the anisotropic hardening behavior of MS1180 steel through experiment and analytical modeling. Dogbone and hydraulic bulging specimens were machined to test the mechanical behavior of MS1180 steel plate under different loading directions and stress states. The loading process was recorded by the three-dimensional digital image correction system. The result uncovers that the strength under equi-biaxial tension is larger than that under uniaxial tension. Mechanical behavior under different loading directions presents the obvious difference related to the plastic strain. Hardening behavior under uniaxial tension and equi-biaxial tension is characterized by the Swift-Voce and polynomial equations, respectively. Three yield functions are adopted to describe the anisotropic behavior, including Yld2000-2d, S-Y2009, and CQN-Chen. A convexity analysis method based on geometric definition is used to determine the convex region of the CQN-Chen yield surface under large strain. By comparing the yield surfaces of the three yield functions under different plastic strain, the CQN-Chen yield function possesses a more flexible and reasonable characterization ability than the Yld2000-2d and S-Y2009 yield functions. The anisotropic hardening behavior of MS1180 steel plate is modeled with an error of less than 0.03 by the CQN-Chen yield function, showing high prediction accuracy.