Calculations of forming limit diagrams

The right-hand side of the forming limit diagram (FLD) was calculated using a Marciniak-Kuczynski analysis with a nonquadratic anisotropic yield criterion. Effects of changing the strain-hardening exponent, n, strain-rate exponent, m, strain ratio, R, stress exponent in the anisotropic yield criterion, a, and the inhomogeneity factor, f, were explored. For a ≥ 6, the effect of R is negligible. The calculated forming limit for plane strain is raised by increased values of n, m, and f and is unaffected by R and a. The slope of the right-hand side is decreased by increased values of n, m, and a, whereas the slope increases with higher f The calculated FLDs agree well with experimental ones determined by in-plane stretching.

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