PSI - Issue 2_B

Ch. F. Markides et al. / Procedia Structural Integrity 2 (2016) 2881–2888 Ch. F. Markides, E. D. Pasiou and S. K. Kourkoulis / Structural Integrity Procedia 00 (2016) 000 – 000

2888

8

4. Discussion and concluding remarks The response of a composite circular disc, subjected to compressive loading between curved jaws, was studied numerically. The crucial role of the intermediate adhesive layer was enlightened. It was pointed out that in order for the stress concentrations, inevitably appearing along the two interfaces characterizing the specific configuration, to be smoothened out the elastic modulus of the intermediate layer should be properly considered. In the ideal case the specific property should be as close as possible to the average value of the elastic moduli of the two semi-discs forming the composite disc. Moreover it was pointed out that the role of the thickness of the interfacial layer is not negligible, however it should be considered in juxtaposition to the relative values of the three elastic moduli, i.e. those of the two semi-discs and that of the adhesive layer. In case the elastic moduli E 1 and E 2 are close enough to each other the role of the adhesive layer’s thickness is diminished assuming that its elastic modulus is similar to these of the two semi-discs. Finally the inclination angle of the interfacial layer with respect to the loading axis was proven also crucial, especial ly in case the adhesive layer tends to become parallel to the loading axis. The latter case is characterized by strong stress concentrations in the immediate vicinity of the disc-jaws contact arcs, especially at the end-points of the two interfaces which is even stronger for the stiffer material, i.e. for semi-disc (2). References ASTM D3967 - 08, 1978. Standard test method for splitting tensile strength of intact rock core specimens, ASTM Volume 04.08 Soil and Rock (I): D420 D5876, 2014. Banks-Sills, L., Interface fracture mechanics - Theory and experiment. International Journal of Fracture, 191, 131-146. Banks-Sills, L., Schwartz, J., 2002. Fracture testing of Brazilian disk sandwich specimens. International Journal of Fracture, 118(3), 191-209. Banks-Sills, L., Konovalov, N., Fliesher, A., 2010. Comparison of two and three-dimensional analyses of interface fracture data obtained from Brazilian disk specimens. International Journal of Materials and Structural Integrity 1(1), 20 – 42. Fairhurst, C., 1964. On the validity of the ‘Brazilian’ test for brittle materials. Journal of Rock Mechanics Mi ning Science & Geomechanics Abstracts, 1, 535-546. Hooper, J. A., 1971. The failure of glass cylinders in diametral compression. Journal of the Mechanics and Physics of Solids, 19, 179-200. ISRM, 1978. Suggested methods for determining tensile strength of rock materials. International Journal of Rock Mechanics Mining Science & Geomechanics Abstracts, 15(3), 99-103. Kourkoulis, S. K., Markides Ch. F., Chatzistergos P., 2012. The standardized Brazilian disc test as a contact problem. International Journal of Rock Mechanics and Mining Sciences, 57,132-141. Kourkoulis, S. K., Markides, Ch. F., Hemsley, J. A., 2013. Frictional stresses at the disc-jaw interface during the standardized execution of the Brazilian disc test. Acta Mechanica, 224(2), 255-268. Markides, Ch. F., Kourkoulis, S. K., 2012. The stress field in a standardized Brazilian disc: The influence of the loading type acting on the actual contact length. Rock Mechanics and Rock Engineering, 45(2), 145-158. Muskhelishvili, N. I., 1963. Some basic problems of the mathematical theory of elasticity, Noordhoff, Groningen, The Netherlands. Timoshenko, S. P., Goodier, J. N., 1970. Theory of elasticity, 3 rd edition, McGraw-Hill, New York.