PSI - Issue 2_A

Takuhiro Hemmi et al. / Procedia Structural Integrity 2 (2016) 2230–2237 Author name / Structural Integrity Procedia 00 (2016) 000–000

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5. Conclusion In our study, we examined the relationship between microscopic structure and arrest toughness. First, we evaluated the relationship between grain size and effective surface energy. As a result, the smaller grain size is, the lower effective surface energy is and the result is different from the real phenomenon. Next, we conducted crack arrest tests, using three kinds of steel pieces which have different grain size. As a result, the smaller grain size is, the larger the arrest toughness ܭ ୡୟ . Finally, we identified effective surface energy by multiscale model using test result. As a result, the smaller grain size is, the higher effective surface energy which made consistent with test result is. The result was contrary to the result of microscopic model. Thus, it is necessary to revise the derivation method of effective surface energy. From results above, it is expected conduct more experiments and analysis as follows for quantification of effective surface energy which is needed crack surface formed. (1) Measuring the plastic work to form tear-ridge per unit area from experiments (2) Revising the formulation of the energy absorption by forming tear-ridge (3) Reviewing the energy absorbing mechanism except forming tear-ridge (4) Reconsidering algorithm and fracture criterion in multiscale model Acknowledgements A part of this work was supported by JSPS KAKENHI Grant Number 16K14410 and Fundamental Research Developing Association for Shipbuilding and Offshore (REDAS). The authors would like to thank them. References Ishikawa. T, Nomiyama. Y, Hagiwara.I, Aihara.S , 1995. Journal of the Society of Naval Architects of Japan, 259, in Japanese. Ohmori. Y, Iwanaga. H, Kawaguchi.Y, Terasaki. F, 1976.: Tetsu-to Hagané, 62, 1017, in Japanese Shibanuma. K, Yamamoto.Y, Yanagimoto. F, Suzuki. K, Aihara.S, Shirahata, H, 2016. Multiscale model synthesis to clarify the relationship between microstructures of steel and macroscopic brittle crack arrest behavior - Part I: Model presentation, ISIJ International, 56(2), 341-349 Yamamoto. Y, Shibanuma. K, Yanagimoto. F, Suzuki. K, Aihara. S, Shirahata. H, 2016. Multiscale model synthesis to clarify the relationship between microstructures of steel and macroscopic brittle crack arrest behavior - Part II:Application to crack arrest test, ISIJ International, 56(2), 350-358 S.Aihara, Y.Tanaka, 2011, A simulation model for cleavage crack propagation in bcc polycrystalline solids, Acta Materialia, 59, 4641–4652. TSL Solutions: OIMAnalysis ver.6.1, 2011 WES TS2816, Simplified test method for brittle crack arrest toughness using press-notched bend specimen, 2015. SIMULA, Abaqus 6.14 Documentation, 2014.