PSI - Issue 28

S.V. Suknev et al. / Procedia Structural Integrity 28 (2020) 903–909 Author name / Structural Integrity Procedia 00 (2019) 000–000

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It is indicated by the results obtained that the modified TCD methods (the modified FFM in particular) properly describe the effect of both the hole size and the boundary conditions on the fracture of quasi-brittle material. 6. Conclusions The field of application of the prevalent TCD-based fracture criteria, whose distinguishing feature is the introduction of an intrinsic material length parameter, is limited to brittle or quasi-brittle fracture with a small process zone. To apply the criteria for cases of quasi-brittle fracture with a developed process zone, it is proposed to abandon the hypothesis of the introduced parameter as a material constant related only to its microstructure. It should be considered as a material constant only in one particular case, which is brittle fracture. For quasi-brittle materials, this parameter is associated with the formation of the fracture process zone and represented by the sum of two terms. The first of them characterizes the material microstructure itself and is a constant, and the second one reflects the formation of inelastic deformations and depends on the plastic properties of the material, the geometry of the specimen, and boundary conditions. The proposed approach was used to modify the TCD methods employed for the prediction of failure under stress concentrations. An experimental study related to the processes of deformation and fracture of quasi-brittle geomaterial with a circular hole under non-uniformly distributed compression has been carried out, and the modified methods have been verified. There is good agreement between the prediction of the critical load at the instance of fracture initiation and the experimental data. Acknowledgements The research was supported by the Russian Foundation for Basic Research under grant number 18-05-00323. References Fuentes, J.D., Cicero, S., Procopio I., 2017. Some default values to estimate the critical distance and their effect on structural integrity assessments. Theoretical and Applied Fracture Mechanics 90, 204–212. Justo, J., Castro, J., Cicero, S., 2020. Notch effect and fracture load predictions of rock beams at different temperatures using the Theory of Critical Distances. International Journal of Rock Mechanics and Mining Sciences 125, 104161. Li, W., Susmel, L., Askes, H., Liao, F., Zhou, T., 2016. Assessing the integrity of steel structural components with stress raisers using the Theory of Critical Distances. Engineering Failure Analysis 70, 73–89. Negru, R., Marsavina, L., Voiconi, T., Linul, E., Filipescu, H., Belgiu, G., 2015. Application of TCD for brittle fracture of notched PUR materials. Theoretical and Applied Fracture Mechanics 80, 87–95. Neuber, H., 1937. Kerbspannungslehre, Grundlagen für eine genaue Spannungsrechnung, Springer-Verlag, Berlin. Novozhilov, V.V., 1969. On a necessary and sufficient criterion for brittle strength. Journal of Applied Mathematics and Mechanics 33, 201–210. Peterson, R.E., 1959. Notch sensitivity, in “Metal Fatigue” . In: McGraw Hill, New York, pp. 293–306. Suknev, S.V., 2015. Fracture of brittle geomaterial with a circular hole under biaxial loading. Journal of Applied Mechanics and Technical Physics 56, 1078–1083. Suknev, S.V., 2019. Nonlocal and gradient fracture criteria for quasi-brittle materials under compression. Physical Mesomechanics 22, 504–513. Taylor, D., 2007. The Theory of Critical Distances: A New Perspective in Fracture Mechanics, Elsevier, Oxford. Taylor, D., 2008. The theory of critical distances. Engineering Fracture Mechanics 75, 1696–1705. Vargiu, F., Sweeney, D., Firrao, D., Matteis, P., Taylor D., 2017. Implementation of the Theory of Critical Distances using mesh control. Theoretical and Applied Fracture Mechanics 92, 113–121. Vedernikova, A., Kostina, A., Plekhov, O., Bragov, A., 2019. On the use of the critical distance concept to estimate tensile strength of notched components under dynamic loading and physical explanation theory. Theoretical and Applied Fracture Mechanics 103, 102280. Wieghardt, K., 1907. Über das Spalten und Zerreisen elastischer Körper. Zeitschrift für Mathematik und Physik 55, 60–103.