PSI - Issue 13

Fuzuli Ağrı Akçay / Procedia Structural Integrity 13 (2018) 1695 – 1701 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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fall within three standard deviations in normal distribution, minimum experimental tensile strength of G60N6 can be approximated as 196 MPa, which is in excellent agreement with the theoretical calculation. Another possible reason for the difference between theoretical and experimental strengths can be the large deviation in graphite spacing of G60N6, given as 41  m (Han et al., 2013).

4. Conclusions

A brittle fracture criterion of tensile mode for initially crack-free bodies is developed using Karr-Akçay energy balance concept. A significant application of the criterion can be determination of (Mode I) fracture toughness of a material simply by uniaxial tensile test specimen. Moreover, the proposed criterion has two additional fundamental uses: (Fracture) strength of a material can be determined if its characteristic length is known, whereas the characteristic length of a material can be obtained if its (fracture) strength is known. Accordingly, tensile strength of a gray cast iron is determined using the proposed criterion within 15% deviation from the experimental result. Although application of the proposed brittle fracture criterion presents encouraging results, the validity of the criterion should be ensured for different materials and constitutive relations (e.g., non-linear elastic stress-strain relationships), as well as multiaxial loading conditions. Additionally, the proposed fracture criterion is applicable to tensile mode fracture only, and extending the criterion to shear mode fracture is underway. The author would like to express his gratitude to Prof. Dr. Dr.-Ing. M. Cengiz Dökmeci for his continuous encouragement to pursue an academic career with maintaining scientific curiosity and excitement. Moreover, the author greatly acknowledges Assoc. Prof. Dr. Captain Veysel Alankaya for his insightful attitude and kindness during the author’ s mandatory military service at the Turkish Naval Academy. Finally, the author appreciates European Structural Integrity Society (ESIS) for paying ECF22 conference fee, as well as I.T.U. Faculty of Naval Architecture and Ocean Engineering for covering ECF22 travelling and accommodation expenses. This work is saved from a predatory publisher with the help of Prof. Jeffrey Beall. The author sincerely appreciates his guidance. Anderson, T. L., 2005. Fracture mechanics: Fundamentals and applications. CRC Press, Boca Raton. Brauer, S. A., Whittington, W. R., Johnson K. L., Li, B., Rhee, H., Allison, R. G., Crane, C. K., Horstemeyer, M. F., 2017. Strain rate and stress state dependence of gray cast iron. Journal of Engineering Materials and Technology 139, 021013. Cotterell, B., 2002. The past, present, and future of fracture mechanics. Engineering Fracture Mechanics 69, 533-553. Dieter, G. E., 1986. Mechanical metallurgy. McGraw-Hill, New York. Gao, X., Faleskog, J., Shih, C. F., Dodds, R. H., 1998. Ductile tearing in part-through cracks: Experiments and cell-model predictions. Engineering Fracture Mechanics 59, 761 – 777. Griffith, A. A., 1921. The phenomena of rupture and flow in solids. Philosophical Transactions of the Royal Society of London Series A 221, 163 – 198. Han, S. Y., Sohn, S. S., Shin, S. Y., Lee, S., Suh, Y. C., 2013. In Situ fracture observation and fracture toughness analysis of pearlitic graphite cast irons with different nodularity. Metals and Materials International 19, 673-682. Karr, D. G., Akçay, F. A., 2016. A criterion for ductile fracture based on continuum modeling of energy release rates. International Journal of Fracture 197, 201-212. Pelekis, I., Susmel, L., 2017. The theory of critical distances to assess failure strength of notched plain concrete under static and dynamic loading. Engineering Failure Analysis 82, 378-389. Taylor, D., 2007. The theory of critical distances: A new perspective in fracture mechanics. Elsevier, Amsterdam. Telichev, I., 2016. Application of the method of singular integral equations to the failure analysis of impact-damaged thin-walled pressurized structures. Engineering Fracture Mechanics 154, 169-179. URL-1, 2017, December 14. Cast iron, Retrieved from https://en.wikipedia.org/wiki/Cast_iron. White, C. V., 2010. Gray iron, in “ ASM Handbook ” , in Volume 1: Properties and selection: Irons, steels, and high-performance alloys. ASM International, Materials Park, pp. 12-32. Acknowledgements References