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Size and crack length effects on fracture toughness of polycrystalline graphite

In this paper, the effects of specimen size and crack length on the fracture toughness of polycrystalline graphite are studied. The experimental results reported in the previous studies showed that the fracture toughness of graphite increase in bigger specimen. | Nội dung Text Size and crack length effects on fracture toughness of polycrystalline graphite Engineering Solid Mechanics 2 2014 183-192 Contents lists available at GrowingScience Engineering Solid Mechanics homepage www.GrowingScience.com esm Size and crack length effects on fracture toughness of polycrystalline graphite J. Akbardoost Faculty of Engineering Kharazmi University Mofatteh Avenue P.O. Box 15719-14911 Tehran Iran ARTICLE INFO ABSTRACT Article history In this paper the effects of specimen size and crack length on the fracture toughness Received January 20 2014 Received in Revised form of polycrystalline graphite are studied. The experimental results reported in the April 10 2014 previous studies showed that the fracture toughness of graphite increase in bigger Accepted 25 April 2014 specimen. It has been also demonstrated that the fracture toughness of graphite is Available online nearly identical in specimens with crack length ratio less than 0.7 but decreases for 24 April 2014 grater crack length ratios. To justify the size and crack length dependency of fracture Keywords Polycrystalline graphite toughness the modified form of maximum tangential stress MMTS criterion which Fracture toughness makes the use of higher order terms in calculating the stress field around the crack tip Size effect is employed. It is shown that the MMTS criterion can provide good estimates for the Crack length effect fracture toughness of graphite obtained from specimen with different sizes. It is also Higher order terms Modified maximum tangential indicated that the MMTS criterion can predict very good the reported experimental stress criterion fracture toughness data for samples with the crack length ratios less than 0.7. 2014 Growing Science Ltd. All rights reserved. 1. Introduction Since graphite has good thermal stability low permeability high corrosion resistance good performance in electrical and thermal conductivity and good thermal shock resistance it is employed .