NONLINEAR KINEMATIC HARDENING RULE PARAMETERS - DIRECT DETERMINATION FROM COMPLETELY REVERSED PROPORTIONAL CYCLING

A methodology for the determination of parameters for superposed, unco upled, A-F type nonlinear kinematic hardening rules is presented for r eversed cyclic plasticity or viscoplasticity. The important aspects of the procedure are presented for general reversed proportional cycling and then special cases of axial-torsional and uniaxial loadings are c onsidered along with several experimental examples. The approach yield s a quantitative estimate of the saturation state of stress for these types of models, directly from experimental responses to reversed prop ortional cycling. Iterations are not required to obtain parameter esti mates, except for the numerical solution to a set of nonlinear algebra ic equations when more than two A-F type rules are superposed to model backstress evolution. (C) 1997 Elsevier Science Ltd.