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デューク大学の研究者が数十年前の強度試験に新たな局面を発見(Duke Researchers Find New Dimensions in Decades-Old Strength Test)

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2024-03-18 デューク大学(Duke)

The schematic of the Brazilian test together with two experiments and their simulationRepresentative experiments, and their corresponding simulation, of Brazilian tests at the onset of fracture

デューク大学の機械工学と材料科学のジョン・ドルボウ教授とイリノイ大学アーバナ・シャンペーン校の土木環境工学のオスカー・ロペス・パミエス教授は、計算破壊力学を協力して研究しており、材料の破壊をよりよく理解し、予測することを目指しています。彼らの研究の中心にあるのは、建設、製造、さらには医療応用に重要な脆性材料の強度を試験するために使用されてきた古い公式を修正することです。彼らの研究では、カルネイロの方法の中心にある式を正確に修正する必要性を強調し、材料が選択および使用される方法に影響を与える可能性があります。

<関連情報>

ブラジルの破壊テストの強さ The strength of the Brazilian fracture test

Aditya Kumar, Yangyuanchen Liu, John E. Dolbow, Oscar Lopez-Pamies
Journal of the Mechanics and Physics of Solids  Available online:28 October 2023
DOI:https://doi.org/10.1016/j.jmps.2023.105473

Abstract

Since its introduction in the 1940s until present times, the so-called Brazilian test has been embraced by practitioners worldwide as a method of choice to indirectly measure the tensile strength of concrete, rocks, and other materials with a large compressive strength relative to their tensile strength. This is because of the ease that the test affords in both the preparation of the specimen (a circular disk) and the application of the loads (two platens compressing the specimen between them). Yet, this practical advantage has to be tempered by the fact that the observations from a Brazilian test — being an indirect experiment in the sense that it involves not uniform uniaxial tension but non-uniform triaxial stress states throughout the specimen — have to be appropriately interpreted to be useful. The main objective of this paper is to carry out a complete quantitative analysis of where and when fracture nucleates and propagates in a Brazilian test and thereby establish how to appropriately interpret its results. We do so by deploying the phase-field fracture theory of Kumar et al. (2020), which has been recently established as a complete theory of fracture capable of accurately describing the nucleation and propagation of cracks in linear elastic brittle materials under arbitrary quasistatic loading conditions. The last section of this paper puts forth a new protocol to deduce the tensile strength of a material from a Brazilian test that improves on the current ISRM and ASTM standards.

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0902鋼構造及びコンクリート
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