A constitutive model of cyclic plasticity

This paper addresses a constitutive model of cyclic plasticity with special emphasis on the yield-point phenomena. In order to point out the deformati on characteristics of a mild steel, four types of experiments were conducte d, i.e. uniaxial tension at several crosshead speeds, cyclic straining, and stress- and strain-controlled ratchetting. A viscoplastic constitutive mod el of cyclic plasticity is proposed on the premise that the phenomena of sh arp yield point and the subsequent abrupt yield drop result from rapid disl ocation multiplication and the stress-dependence of dislocation velocity. B esides, cyclic plasticity behavior, such as the Bauschinger effect, cyclic hardening/softening characteristics and ratchet-strain accumulation, is des cribed by some kinematic and isotropic hardening rules. The cyclic stress-s train responses predicted by this model agree well with the corresponding e xperimental results. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.