Issue 75

R. Ince et alii, Fracture and Structural Integrity, 75 (20YY) 435-462; DOI: 10.3221/IGF-ESIS.75.30

Utilizing cylindrical and cubical specimens with edge notch to determine size-independent fracture quantities of rock materials

R. Ince, E. Eren Firat University, Faculty of Engineering, Department of Civil Engineering, Elazig, Turkey

rince@firat.edu.tr, http://orcid.org/0000-0002-9837-8284 eeren@firat.edu.tr, http://orcid.org/0000-0001-5282-398X

Citation: Ince, R., Eren, E., Utilizing cylindrical and cubical specimens with edge notch to determine size-independent fracture quantities of rock materials, Fracture and Structural Integrity, 75 (2026) 435-462.

Received: 04.10.2025 Accepted: 11.12.2025 Published: 11.12.2025 Issue: 01.2026

Copyright: © 2026 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

K EYWORDS . Crack Closure Integral (CCI), Double-K model, Single notched cube bend specimen, Straight-notched disk bend specimen, Two-parameter model (TPM).

I NTRODUCTION

n materials science, clay products such as bricks, natural stones, and concrete are generally classified as ceramic materials. From ancient times to the present day, bricks and natural stones such as limestone, granite, and sandstone, as well as Roman concrete, have been widely used in buildings, bridges, and retaining walls. These materials are categorized as quite brittle in materials science, meaning that while their compressive strength is reasonable, their tensile strength is poor. Therefore, in practice, ceramic materials are simulated using the Mohr-Coulomb criterion, one of the classical fracture theories, where materials are assumed to be flawless. Moreover, bricks, natural stones, and concrete contain many voids, both open and closed. In the 1920s, experimental research on brittle materials such as glass revealed that no material was perfect. Subsequently, the principle of linear elastic fracture mechanics (LEFM) was introduced. Irwin [1] improved this theory in the 1950s and proposed two equivalent material quantities, fracture toughness, and the critical strain energy release rate, to simulate I

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