PSI - Issue 18

Mehdi Mokhtarishirazabad et al. / Procedia Structural Integrity 18 (2019) 457–471 M. Mokhtarishirazabad / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 8, shows the R-curve of the three SENB_B20_0.5 samples; all samples had the same geometry and dimensions. A significant discrepancy in the measured crack extension by unloading compliance (UC), Δ a UC was observed. However, Fig. 9 shows that the loading sequences and response of the samples were very similar. The scatter is due to variation in the UC in the load-CMOD graphs of the same geometry. In Fig. 9, sample SENB_B20_0.5_01 differs slightly to the other two specimens. This sample was tested at a higher rate and larger displacement intervals. Room temperature rate dependency has been observed in stainless steel 316L and have been attributed to cold creep (Moreton and Sellings 1989); the initial part of the curve is much steeper than the theoretical blunting line in the plot, which can be attributed to the underestimation of the crack length measured by UC.

Fig. 7. The graph of load as a function of CMOD for samples with thicknesses of 5, 10 and 20 mm and a/W = 0.5 and 0.2.

Fig. 8. R-Curve for SENB_B20_0.5 samples.