An investigation of the crack propagation under the creep-fatigue interaction in C(T) specimens of P2M steel was carried out. Numerical calculations included the determination of the stress-strain state fields for the viscoelastic material, as well as the distributions of stress triaxiality, nonlinear stress intensity factors, and the C-integral along the crack front in specimen with different thickness. The interpretation of the experimental results under fatigue-creep interaction is given by the elastic and nonlinear stress intensity factors in terms of the traditional and new normalized cyclic fracture diagrams. Considering the size effects through the creep-dominated stress intensity factors caused differences in the crack growth behavior. In specimens with the same geometry, the crack growth rate under the creep-fatigue interaction increased monotonically compared with harmonic fatigue, and the superposition of fatigue and creep contributions shows an order of magnitude increase in the total crack growth rate with respect to the pure creep.

In this work, the simplified Lemaitre damage model was integrated into the ANSYS finite element calculation software. The model is implemented as a dynamically linked library of custom material for 2D problems. The model was tested on a cylindrical specimen with an annular cut. The stages of damage accumulation in the numerical experiment coincide with similar numerical experiments known in the literature.

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