PSI - Issue 23

Lucie Malíková et al. / Procedia Structural Integrity 23 (2019) 487–492

492

Lucie Malíková et al. / Structural Integrity Procedia 00 ( 2019) 000 – 000

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5. Conclusions

The effective crack model (ECM) has been applied on three cylindrical specimens from Silesian granite that had been supplied by a chevron-type notch and loaded in three-point bending. The dimension of the real specimens as well as the load – CMOD curves measured during experiment have been used as inputs for finite element simulations. The non-linear ECM model enabled calculating of the maximum value of the effective fracture toughness and their comparison to the values of the classical fracture toughness obtained from purely elastic solution. It has been proved that when the non-linear ECM was applied on quasi-brittle materials (selected rock in the case of this paper), the more precise values of the fracture properties can be obtained contrary to the underestimated values of the fracture toughness calculated based on the classical linear elastic fracture mechanics. The aim of future works is to derive the appropriate function of geometry, which would allow determination of effective fracture toughness K Ic,eff .

Acknowledgements

The financial support provided by the Czech Science Foundation (project No. 18-12289Y) is gratefully acknowledged. Presented work was also supported by the Ministry of Education, Youth and Sports of the Czech Republic (project No. NPU I – LO1406) and by the project for the long-term conceptual development of research organisations (RVO: 68145535).

References

Bažant, Z.P., Planas, J. 1998 . Fracture and size effect in concrete and other quasibrittle materials. CRC Press, Boca Raton and London, 640 p. Fowel, RJ. 1995. Suggested method for determining mode I fracture toughness using cracked chevron notched Brazilian disc (CCNBD) specimens. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 32, 1, 57 –64 . Halfar, P. 2018. Evaluation of fracture test of selected core - drilled cylindrical specimen. Diploma Thesis. Brno University of Technology, 65 p. Halfar, P., Frantík, P., Šimonová, H., Daněk, P., Keršner, Z., Vavro, L., Vavro, M. 2018. Effective crack model application for analysis of chevron notched cylindrical specimens fracture response. Structural Reliability and Modelling in Mechanics, Ostrava (in Czech). Karihaloo, B.L. 1995. Fracture mechanics and structural concrete. Longman Scientific an Technical, Essex. Koutník, P., Antoš, P., Hájková P., Martinec, P., Antošová, B., Ryšánek, P., Pacina, J., Šancer, J., Ščučka, J., Brůna, V., 2015. Decorative stones of Bohemia, Moravia and Czech Silesia. Jan Evangelista Purkyně University in Ústí na Labem, 495 p. (in Czech). Kuruppu, MD., Obara, Y., Ayatollahi, MR., Chong, KP., Funatsu, T. 2014. ISRM - Suggested method for determining the mode I static fracture toughness using semi - circular bend specimen. Rock Mechanics and Rock Engineering 47, 1, 267 – 274. Ouchterlony, F., 1988. Suggested methods for determining the fracture toughness of rock. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 25, 2, 71 – 96. Rybařík, V., 1994. Noble building and sculptural stone of the Czech Republic. Industrial Secondary School of Stonework and Sculpture in Hořice, 218 p. (in Czech). Shah, S.P., Swartz, S.E. and Ouyang, C., 1995. Fracture mechanics of structural concrete: applications of fracture mechanics to concrete, rock, and other quasi - brittle materials. John Wiley & Sons, Inc., New York, 588 p. Vavro, L. 2015. Fracture toughness of rock and its determination for geomechanical evaluation of rock and rock mass. Ph.D. Thesis. VSB Technical University of Ostrava, 93 p. Vavro, L., Malíková, L., Frantík, P., Kubeš, P., Keršner, Z., Vavro, M. 2019. An advanced assessment of mechanical fracture parameters of sandstones depending on the internal rock texture features. Acta Geodynamica et Geomaterialia 16, 2, 157 – 168. Wei, MD., Dai, F., Xu, NW Zhao, T., Liu, Y. 2017. An experimental and theoretical assessment of semi - circular bend specimens with chevron and straight - through notches for mode I fracture toughness of rocks. International Journal of Rock Mechanics and Mining Sciences 99, 28 –38 .