PSI - Issue 39

Aljaž Ignatijev et al. / Procedia Structural Integrity 39 (2022) 89 – 97 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3. Crack propagation was determinate until equivalent stress intensity factor range become higher than the critical stress intensity factor, i.e. ∆ K ≥ K Ic .

Fig. 5. Equivalent von Mises stress field at the initial crack length (load case 3).

Fig. 6. Equivalent von Mises stress field at the critical crack length (load case 3).

Based on the values of the equivalent stress intensity factor range for each crack increment, a polynomial trendline has been created in MS Excel. By inserting a critical stress intensity factor into a polynomial equation, the exact critical length of the crack was calculated. This polynomial equation was insert in an integrated equation (4) of the Paris law, from which the number of cycles to failure was calculated for each load case. Fig. 6 shows the equivalent von Mises stress field at the critical length of the crack for the load case 3. ∫ 0 = 1 ∫ [ ∆ ( )] (4)