Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
780889 | International Journal of Fatigue | 2013 | 13 Pages |
An improved unified cyclic viscoplastic material model for high temperature fatigue of P91 steel is presented. The primary enhancement over existing models is in relation to strain-rate independence of parameters, for accurate interpolation and extrapolation across a range of strain-rates and stress regimes, as relevant to flexible operation of high temperature power generation plant. The model combines a hyperbolic sine constitutive equation with anisothermal cyclic evolution of isotropic and kinematic hardening variables. The material model is developed from a thermodynamic framework and is implemented in multi-axial form within a user material subroutine. The user material subroutine is calibrated and validated for P91 steel across a range of cyclic (isothermal fatigue and thermo-mechanical fatigue) and non-cyclic high temperature loading conditions. A novel method for the identification of the cyclic viscoplastic material parameters is also presented.
► Development of a cyclic sinh unified viscoplasticity constitutive model. ► Model applied to P91 steel under high temperature, cyclic loading conditions. ► Novel calibration technique for the identification of the viscoplastic parameters. ► sinh model allows the strain rate effect of 9Cr steels to be modelled accurately.