PSI - Issue 42

B.Aydin Baykal et al. / Procedia Structural Integrity 42 (2022) 1350–1360 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4: Dependence of critical volume on selected critical stress Applying the ASTM correction factor as described in the introduction section indeed showed that it was inaccurate at determining the corresponding critical area of a full-sized specimen, particularly at high K values. This is represented on Figure 5.

A* for 2000 MPa (1T) A* for 2000 MPa (0.18T) ASTM 1T-adjustment

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

OK

Inaccurate

A* for 2000 MPa (1T) (mm^2)

0

20 40 60 80 100 120 140 160

K, (MPam 1/2 )

Fig. 5: Inaccuracy of ASTM correction in above threshold K value during scaling from 0.18T CT specimen size Figure 5 clearly shows that above a threshold value of about 40 MPa.m 1/2 , the standard ASTM correction fails to describe the critical area of a 1T-sized specimen accurately. The underestimation of critical area leads to an overestimation of fracture toughness based on the local approach to fracture, potentially leading to dangerous situations in highly-loaded practical applications. This behavior is further demonstrated in Figure 6, where, above the same threshold value, the simulated and calculated values of the stress intensity K on a 1T-CT specimen lose