LOCALIZATION OF DEFORMATION IN RATE SENSITIVE POROUS PLASTIC SOLIDS
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The effect of material rate sensitivity on the localization of deformation in a porous visco-plastic solid is examined under plane strain tension and axisymmetric tension conditions. The plastic flow rule proposed by Gurson , modified to account for material rate sensitivity, is adopted to model the plastic softening behavior that arises due to void nucleation and growth. An initial imperfection in the form of a planar band is assumed and a material instability is sought as the deformation proceeds. Comparisons are made with the results of a rate-independent analysis . The present rate-dependent results show that the retardation effect on flow localization is larger when the material is more rate-sensitive, and that, with a given rate sensitivity, the retardation effect on flow localization is greater in plane strain tension than in axisymmetric tension. Results are also obtained by employing parameter values representative of spheroidized carbon steels studied by Fisher , and the predictions of the model are in good agreement with experimental observations. 1983 Martinus Nijhoff Publishers.