Issue 50

M. Eremin et alii, Frattura ed Integrità Strutturale, 50 (2019) 38-45; DOI: 10.3221/IGF-ESIS.50.05 45 S UMMARY roduction of advanced materials on the basis of metal oxides ceramics is booming production area. The creation of materials with necessary mechanical properties is an actual problem of materials science, which is solved on the basis of detailed experimental studies. However, the involvement of modern technologies based on CAD/CAM can significantly reduce costs when designing new materials. In this context, the creation of digital twins of materials and the formulation of fracture criteria is one of the most urgent tasks of materials science. In this work, the FEM simulation-based approach is utilized. A digital twin of a laboratory specimen was created. Specimens were obtained by sintering powder of technically pure aluminum oxide. Microstructure studies were performed, as well as experiments on three-point bending of laboratory specimens. Numerical simulation of the specimen’s deformation and fracture at three-point bending loading was performed in a three- dimensional formulation. The inelastic deformation of the sample is described in the work by the Drucker – Prager model with the non-associated plastic flow rule; the deformation criterion which is based on the accumulated intensity of inelastic strain is selected as the fracture criterion. All parameters of the model, with the exception of the dilatancy coefficient, were validated on the basis of experimental data and correspond to the effective characteristics, which have been recently obtained from the mesoscale simulation. Alumina ceramics demonstrate typical brittle behavior, the crack path is rather tortuous with the dominant mode I mechanism. The results of the numerical simulation are in good agreement with the experimental study. A CKNOWLEDGMENTS his work was granted by the Fundamental Research Program of the State Academies of Sciences for 2013-2020, the direction of research III.23 and with the support of the Tomsk State University Competitiveness Improvement Program. Authors also express gratitude to an anonymous reviewer whose comments helped to improve an article. R EFERENCES [1] Ruys, A. (2019). Processing, structure, and properties of alumina ceramics, In: Alumina ceramics: Biomedical and clinical applications, Woodhead Publishing, pp. 71–121. DOI: 10.1016/C2017-0-01189-8. [2] Staub, D., Meille, S., Le Corre, V., Rouleau, L. and Chevalier, J. (2016). Identification of a damage criterion of a highly porous alumina ceramic, Acta Materialia, 107, pp. 261–272. DOI: 10.1016/j.actamat.2016.01.071. [3] Savija, B., Smith, G.E., Liu, D., Schlangen, E. and Flewitt, P.E.J. (2019). Modelling of deformation and fracture for a model quasi-brittle material with controlled porosity: Synthetic versus real microstructure, Engineering Fracture Mechanics, 205, pp. 399–417. DOI: 10.1016/j.engfracmech.2018.11.008. [4] Grigoriev, A., Shilko, E., Skripnyak, V., Smolin, A. and Psakhie, S. (2014). Multiscale numerical study of fracture and strength characteristics of zirconium alumina concrete with use of the particle-based MCA method, Procedia Materials Science, 3, pp. 936–941. DOI: 10.1016/j.mspro.2014.06.152. [5] Mikushina, V.A. and Smolin, I.Yu. (2018). Simulation of mesoscopic fracture of ceramics with hierarchical porosity, AIP Conference Proceedings, 2053, 030041. DOI: 10.1063/1.5084402. [6] Johnson, G. (1977). High-velocity impact calculations in three dimensions, Journal of Applied Mechanics, 44, pp. 95– 100. DOI:10.1115/1.3424022 [7] Drucker, D.C. and Prager, W. (1952). Soil Mechanics and plastic analysis or limit design, Q. Applied Math., 10, pp. 157– 165. [8] Makarov, P.V., Eremin, M.O. and Kostandov, Yu.A. (2014). Prefracture time of gabbro specimens in a damage accumulation model, Physical Mesomechanics, 17, pp. 199–203. DOI: 10.1134/S1029959914030047. P T