PSI - Issue 5

Yoichi Kayamori et al. / Procedia Structural Integrity 5 (2017) 286–293 Yoichi Kayamori et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 6 Relationship between the plastic rotational factor and the ratio of crack length to specimen width.

The average r p obtained in the study was about 0.52 in both Y/T steel models, and the value is compared with reference r p in Fig.6. The r p of 0.52 is close to 0.50, which is calculated by using Eq.(4) in WES1108 for a 0 /W =0.5, and is located between 0.58(Merkle & Corten) and 0.45 (Shiratori & Miyoshi). The r p of 0.52 is therefore consistent with conventional r p values, and is reasonably used for CTOD calculation. However, r p was calculated only for a 0 /W =0.5 in this study. r p is required for wider range of a 0 /W in terms of CTOD-R curve evaluation, and further investigation should be carried out in the future.

5. Concluding remarks

In this study, 3-D elastic-plastic finite element analysis was conducted by using a stepped notch 1T C(T) specimen model of a 0 /W =0.5 for low and high Y/T steels, and rotational deformation was investigated in the model. r p was determined by using the distribution of strain increments, and the effect of Y/T on r p was small. The average r p in both Y/T steels was 0.52, and the value is consistent with conventional r p .

Acknowledgements

This study was partly conducted in the CTOD Toughness Evaluation Committee of the Japan Welding Engineering Society. Useful discussions in the committee are greatly appreciated.

References

ASTM International, 2008, Standard Test Method for Measurement of Fracture Toughness, ASTM E1820. British Standards Institution, 1991, Fracture Mechanics Toughness Tests. Method for Determination of K IC , Critical CTOD and Critical J Values of Metallic Materials, BS7448-1. DNV GL, 2015, Fabrication and Testing of Offshore Structures, DNVGL-OS-C401. Donato, G. H. B., Ruggieri, C., 2006, Estimation Procedure for J and CTOD Fracture Parameters Using Three-Point Bend Specimens, Proceedings of the 6th International Pipeline Conference, IPC2006-10165, 1-9.