Mode I and mixed mode fracture studies in brittle materials using the Brazilian disc specimen

Abstract

High Strength Cement Mortar (HSCM) with very fine sand exhibits a typical brittle behavior. In the present work, a linear elastic fracture mechanics based model is used for the fracture studies conducted On this material. The experimental testing program is based on the diametral compression test of disc specimens containing an internal slant crack. Under the Mode I loading condition, the test method which has been previously used is applied to determine the critical value of the stress intensity factor, Klo for HSCM. The same disc specimen is also tested under combined Mode I and Mode II loading conditions. By changing the notch orientation angle with respect to the loading direction, the mode of fracture is varied from pure Mode I to Mixed-Mode. Based on the Mixed-Mode fracture envelope, it is shown that the disc specimen which is currently used for several brittle materials provides a wide range of IK iiI/KI ratios. In pure Mode I loading case, after determining Klo it is possible to obtain the graph of normalized critical load versus normalized crack length. For the purpose of comparison, some available experimental data on Mode I and/or Mixed Mode fracture of some other brittle materials such as glass, sintered carbide, and polymethyl methacrylate (PMMA) were also evaluated. It can be concluded that there is a good fit between the experimental results and the theory.1359-5997 9 2004 RILEM. All rights reserved. RESUMI~ Les mortiers dl tr~s haute r~sistance (MTHR) pr@ar~s avec du sable tr~s fin ont exhibit~ un comportement (ypiquement fragile. Dans eel article un

Mode ІІ fracture study of rocks using Brazilian disk specimens

“…Krishnan et al [4], Khan and Al-Shayea [5], Chang et al [6], Al-Shayea [7], Ayatollahi et al [8], Lanaro et al [9] have also used the CSTBD specimen to determine mixed mode fracture toughness of various rock types. Yamauchi [34] and Atahan [35] have conducted a series of mixed mode fracture toughness experiments on graphite and concrete using the CSTBD specimen. The frequent use of this specimen makes it essential to propose an appropriate criterion for estimating the values of mode I and mode II fracture toughness which are obtained from the CSTBD specimen.…”

Brittle fracture evaluation of a fine grain cement mortar in combined tensile‐shear deformation

“…carried out a set of combined mode fracture toughness tests on a newly developed structural material called high strength cement mortar (HSCM) using CCBD samples. This material has very fine grains and fails in a brittle manner when subjected to mechanical loading 1 . However, the experimental results obtained from fracture tests on the HSCM specimens do not comply with the theoretical predictions.…”

“…However, the nonlinear region in some of the quasi‐brittle materials like rocks and fine grain cement mortars or in large structures like dams are very often small relative to the characteristic dimensions of the cracked component (like the crack length, specimen thickness, ligament, etc.). For such cases, the components are usually susceptible to brittle fracture due to sudden extension of their inherent cracks and their fracture behaviour can still be investigated by means of LEFM principles 1–6 …”

“…The obtained data from these experiments are often compared with the fracture criteria mentioned earlier. Recently, Atahan et al 1 . carried out a set of combined mode fracture toughness tests on a newly developed structural material called high strength cement mortar (HSCM) using CCBD samples.…”

Determination of Stress Intensity Factor in Concrete Material Under Brazilian Disc and Three-Point Bending Tests Using Finite Element Method

“…Meanwhile many studies were carried out [12] on fracture toughness of self-compacting concrete. Recent publications [13,14] have shown that fracture mechanics has now been established as a fundamental approach that can explain certain nonlinear aspects of concrete behaviour, help to prevent This paper uses tow approaches to analyze the crack propagation of cracks three-point bending concrete beam and Brazilian disk with initial crack based on determination of stress intensity factor analytically starting from weight functions [15] and numerically using the finite element software platform Abaqus, and compares with the features in simulating soften behaviour for various concrete fracture models.…”