PSI - Issue 42

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Procedia Structural Integrity 42 (2022) 202–209

23 rd European Conference on Fracture - ECF23 The circularly truncated Brazilian disc Christos F. Markides, Stavros K. Kourkoulis* National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Mechanics, Laboratory for Testing and Materials, Theocaris Building, Zografou Campus, 157 73, Greece 23 rd uropean onference on Fracture - F23 ir l rl tr t r ili is hristos . arkides, tavros . ourkoulis* National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Mechanics, Laboratory for Testing and Materials, Theocaris Building, Zografou Campus, 157 73, Greece

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 Abstract The Circularly Truncated Brazilian Disc test is here proposed, as an alternative to the classical Brazilian Disc test, in order to confront the premature fracture often observed at the disc-loading platen contact area, which undermines the validity of the re sults of the test. Using the configuration proposed, a predefined contact length is achieved, which is long enough to reduce the intensity of the stress field at the disc ’s periphery and ensuring valid outcomes of the test independently of the materials involved. © 2 The Authors. Published by ELSE IER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of 23 rd European Conference on Fracture - ECF23. Keywords: Brazilian Disc; Circularly Truncated Brazilian Disc; Flattened Brazilian Disc; Complex potentials; Tensile strength. 1. Introduction Almost eight decades after it was introduced by Carneiro (1943) and Akazawa (1943) the Brazilian Disc (BD) test is still the most popular alternative to the direct tensile test for obtaining the tensile strength of brittle materials. However, its validity has been strongly criticized over the years, mainly due to the premature fracture observed at the disc-loading platen contact region (instead of the center of the disc) (Fairhurst 1964; Hobbs 1965; Hooper 1971). In this direction, apart the change of the shape of the loading platens (curved jaws (ISRM 1978) instead of flat platens (ASTM 2008)), modified specimens have been proposed, including, among others, the Circular Ring (CR) (Jaeger & Hoskins 1966; Hudson 1969; Mellor & Hawkes 1971) and the Flattened Brazilian Disc (FBD) (Wang et al. 2004; Wang & Wu 2004). However, the discussion is still open, and based on the experience gained over these years the question that is to be answered is whether the outcomes of any “indirect” tension test are actually representing the tensile strength of the Abstract The Circularly Truncated Brazilian Disc test is here proposed, as an alternative to the classical Brazilian Disc test, in order to confront the premature fracture often observed at the disc-loading platen contact area, which undermines the validity of the re sults of the test. Using the configuration proposed, a predefined contact length is achieved, which is long enough to reduce the intensity of the stress field at the disc ’s periphery and ensuring valid outcomes of the test independently of the materials involved. © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of 23 rd European Conference on Fracture - ECF23. Keywords: Brazilian Disc; Circularly Truncated Brazilian Disc; Flattened Brazilian Disc; Complex potentials; Tensile strength. 1. Introduction l ost eight decades after it as introduced by Carneiro (1943) and kaza a (1943) the Brazilian isc (B ) test is still the ost popular alternative to the direct tensile test for obtaining the tensile strength of brittle aterials. o ever, its validity has been strongly criticized over the years, ainly due to the pre ature fracture observed at the disc-loading platen contact region (instead of the center of the disc) (Fairhurst 1964; obbs 1965; ooper 1971). In this direction, apart the change of the shape of the loading platens (curved ja s (ISR 1978) instead of flat platens ( ST 2008)), odified speci ens have been proposed, including, a ong others, the Circular Ring (CR) (Jaeger oskins 1966; udson 1969; ellor a kes 1971) and the Flattened Brazilian isc (FB ) ( ang et al. 2004; ang u 2004). o ever, the discussion is still open, and based on the experience gained over these years the question that is to be ans ered is hether the outco es of any “indirect” tension test are actually representing the tensile strength of the

* Corresponding author. Tel.: +30 210 7721263; fax: +30 210 7721302. E-mail address: stakkour@central.ntua.gr * Corresponding author. Tel.: +30 210 7721263; fax: +30 210 7721302. E-mail address: stakkour central.ntua.gr

2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of 23 rd European Conference on Fracture - ECF23 2452-3216 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of 23 rd European Conference on Fracture - ECF23

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.025