PSI - Issue 16

Grzegorz Lesiuk et al. / Procedia Structural Integrity 16 (2019) 51–58 Grzegorz Lesiuk et al. / Structural Integrity Procedia 00 (2019) 000 – 000

57

7

Fig. 8. Microscopic view on the fatigue fracture surface of the tested P355NL1 specimen (load angle  =45°, R=0.05) 0.4 mm from precrack tip

a

b

Fig. 9. Last stage of the fatigue crack growth, the fatigue fracture surface of the tested P355NL1 specimen (load angle  =45°, R=0.05) . Last stage of the fatigue crack growth - enlarged fatigue fracture surface of the tested P355NL1 specimen (load angle  =45°, R=0.05)

4. Conclusions

Based on the performed experimental, fatigue fracture tests and numerical analysis, the following conclusions can be drawn:  The proposed experimental technique can be standardized in fatigue crack growth rate tests.  The proposed  Keq stress intensity factor equivalent describes well mixed mode fatigue crack growth for a fixed R-ratio.  A novel, elastic-plastic fracture mechanics parameter  S* describes the kinetics of fatigue crack growth rate under mixed mode loading conditions synonymously without the influence of stress ratio R.  Further experiments and numerical simulations are required for generalization of the proposed energy approach for variable amplitude loading considering proportional and non-proportional loading type.

Acknowledgements

This work was financially supported by the Wrocław University o f Science and Technology grant No. 0401/0012/18