A non-quadratic plane stress yield function for orthotropic sheet metals

In this article, a new plane stress yield function for orthotropic sheet metals called ‘Yld2003’ is proposed. The yield function contains eight anisotropy parameters which can be fitted to selected experimental input data. The main attractivity of the new yield function lies in its very simple mathematical form which makes it very effective and thus quite interesting for implementation in finite element codes. Special attention is paid to the flexibility of the new yield function to reproduce experimental input data. Some applications to orthotropic sheet materials and comparison to the recent yield function ‘Yld2000-2D’ proposed by Barlat et al. [F. Barlat, J.C. Brem, J.W. Yoon, K. Chung, R.E. Dick, S.-H. Choi, F. Pourboghrat, E. Chu, D.J. Lege, Plane stress yield function for aluminium alloy sheets – part 1: theory, Int. J. Plast. 19 (2003) 1297–1319] confirm the capabilities of the proposed yield function. Furthermore, it is shown that the proposed yield function has nearly the same flexibility like Yld2000-2D.