Hole expansion simulation of high strength steel sheet

Abstract

The deformation behavior of high-strength steel sheet during hole expansion is investigated both experimentally and analytically to clarify the effects of the material model (anisotropic yield function) on the finite element simulation of a hole expansion. The test material used in the hole expansion test is a dual-phase steel alloy with a tensile strength of 780 MPa. The elastic-plastic deformation behavior of the test material is precisely measured using biaxial tensile tests with cruciform specimens to determine the appropriate anisotropic yield function for the test material. Moreover, forming simulations of the hole expansion using selected yield functions are carried out. The Yld2000-2d function [Barlat, F., Brem, J. C., Yoon, J. W., Chung, K., Dick, R. E., Lege, D. J., Pourboghrat, F., Choi, S. H., and Chu, E., Int. J. Plasticity, 19 (2003), 1297-1319.] with an exponent of 4 has given the closest agreement with the experimentally measured contours of plastic work and the directions of the plastic strain rates. It was also found that the Yld2000-2d function with an exponent of 4 has given the closest agreement with the observed thickness distribution along the expanded hole edge. Consequently, anisotropic yield functions significantly affect the predictive accuracy of the deformation behavior of a sheet during a hole expansion