Crack initiation prediction under complex thermomechanical loading

As creep-fatigue was mainly studied in uni-axial tension, it is shown here how to proceed with materials experiments and calculations subjected to multi-axial loading and when temperature varies in time and space. The constitutive equations used are those of elasto-visco-plasticity coupled or not, to damage, with isotropic and kinematic hardening. It is shown that the unified damage law first proposed for ductile failure and then for fatigue may also be applied to multi-axial creep-fatigue interaction with a new expression of the damage threshold.