Metalworking science and engineering: by E.M. Mielnik, McGraw-Hill, New York, 1990. ISBN 0-07-041905-1, xix+976 pages, illustrated, US $70.95

Abstract

The forming-limit curve (FLC) is a very useful diagnostic tool for trouble shooting in sheet-metal forming industries. A number of studies have been made to construct forming-limiting curves for various sheet metals. These methods generally lack simplicity and also have limitations in terms of applicability in an integrated computer modelling environment. The FLC depends on the pre-strain and the strain path. However, a forming-limit stress curve (FLSC) is independent of the strain path, and FLCs can be derived from the FLSC for several strain paths.In this paper, a new method of constructing FLCs is proposed in terms of readily measurable material properties from a tensile test. From the knowledge of a single limit yield stress, e.g., the maximum tensile stress, a limit yield stress curve can be determined, assuming that the material follows Hill's yield criterion and isotropic hardening model. The FLC can now be developed by using the Hollomon strain-hardening equation, Hill's anistropy yield criteria and the Levy-Mises equation. The predictions of the proposed model are compared with published experimental data for some low-carbon steels. This method can be integrated easily into any computer analysis of sheet-metal forming and requires only simple tensile properties of the material of interest.