PSI - Issue 39

R. Yarullin et al. / Procedia Structural Integrity 39 (2022) 364–378 Author name / Structural Integrity Procedia 00 (2021) 000–000

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deepest point of the crack front with respect to the crack front intersection with the free surface (break through point) of the tested specimens as a function of complex stress state.

Fig. 16. Crack growth rate on the free surface as a function of elastic equivalent SIFs for both alloys and different loading conditions.

Fig. 17. Crack growth rate as a function of equivalent SIFs for different crack front points and different loading conditions.

Conclusions This study aims at evaluating the fatigue crack growth rate of D16T and B95AT Al-alloy, both numerically and experimentally. The tests were carried out on hollow cylindrical specimens with initial semi-elliptical notch undergoing complex stress state. Despite the very complex stress state at the crack front, the FEM numerical analyses, conducted using the MTS criterion for crack path assessment and a calibrated formula for Keq evaluation, adequately retrace the experimental data; instead, a loss of accuracy can be observed in the last propagation steps, in correspondence of the intersection between the crack front(s) and the specimen’s internal cavity. Further investigations may be conducted to understand the nature of this misalignment, by trying different deflection angle criteria (e.g. Maximum Shear Stress (MSS) or Modified Strain Energy Release Rate (MSERR)), improving the calibration of the