Influence of strain-rate sensitivity on necking and instability in sheet metal forming

Li, MY Chandra, A

My. Li et A. Chandra, Influence of strain-rate sensitivity on necking and instability in sheet metal forming, J MATER PR, 96(1-3), 1999, pp. 133-138

22

INGLESE

Article

Material Science & Engineering

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY

0924-0136 → ACNP

96

1-3

1999

133 - 138

ISI

0924-0136(19991101)96:1-3<133:IOSSON>2.0.ZU;2-2

Analytical closed form solutions based on a linear perturbation analysis ar e obtained to predict limit strains for rate sensitive materials. A closed form solution, independent of the choice of yield criterion, is first obtai ned for the negative minor strain regime of the forming limit diagram (FLD) . The Von Mises yield criterion is invoked next, and the limit strains corr esponding to the positive minor strain regime of the FLD are obtained. Pred ictions from the analytical model are then compared to experimental observa tions. It is noted that the effective limit strain is enhanced by strain ra te sensitivity of the material. It is also observed that the effective limi t strain is not influenced by the prior strain path, but rather by the inst antaneous strain rate ratio in the final stage of the quasi-stable deformat ion. (C) 1999 Elsevier Science S.A. All rights reserved.