| Popis: |
In this paper, we present a new macroscopic isotropic yield criterion expressed in terms of the principal values of the stress deviator that captures the asymmetry in yielding between tension and compression. Comparisons with the results of polycrystalline simulations performed by Hosford and Allen show that this isotropic criterion describes very well the asymmetry in yielding due to activation of twinning. Furthermore, extensions of this criterion to orthotropy are presented. To introduce anisotropy we use two approaches: (a) the generalized invariants approach of Cazacu and Barlat, and (b) the linear transformation approach (Barlat et al.). The ability of the proposed formulations to describe both the asymmetry and anisotropy in yielding of hcp (Mg‐Li) sheet is demonstrated. |
