Resumen de Experimental parameter estimation for nonproportional cyclic viscoplasticity: Nonlinear kinematic hardening rules for two waspaloy microstructures at 650°C

J.C. Moosbrugger

• An earlier reported approach for estimating backstress from uninterrupted, biaxial strain-controlled, nonproportional tests is applied to two different heat treatments of Waspaloy at 650°C. These results are then used to compute backstress histories from cyclic proportional tests. Information regarding the appropriate number of nonlinear kinematic hardening rules for use in viscoplasticity models as well as estimates of the values of the parameters in the kinematic hardening rules are obtained from direct analysis of the experimental data. Complete sets of isothermal model parameters are presented for both heat treatments, and model results are compared with experimental results for several nonproportional, cyclic, strain-controlled test histories. It is shown that the nonlinear kinematic hardening rules determined using the presented methods allow a faithful description of the subtle differences in stress space response paths for the two different heat treatments. Isotropic hardening for the two heat treatments under the experimental conditions is also discussed.