PSI - Issue 5

D. Rozumek et al. / Procedia Structural Integrity 5 (2017) 896–903 D. Rozumek et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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a)

b)

Fig. 7. Comparison of the experimental results for  =  = 45  and mode: a) I and II, b) I and III.

a)

b)

Fig. 8. Comparison of the experimental results for mixed mode condition: a) I+II, b) I+III.

4. Conclusions

The following conclusions from the test results for fatigue crack growth in S355 steel under mixed mode can be drawn:  Under mixed mode condition I+II the fatigue lifetime increase with the loading angle value. It is caused by the decreasing of the K I .  The fatigue crack growth process under mixed mode condition I+II is well described by proposed equivalent stress intensity factor  K eq .  Increase of the angle  determining a ratio of the torsional moment to the bending moment causes decrease of the fatigue life.  For  = 45  and mode I and III, a higher crack growth rate is observed for mode I, which goes into mode III domination.