Numerical Simulation of the Effect of Loading Angle on Initial Cracks Position Point: Application to the Brazilian Test

Abstract

The Brazilian Test is the most used test to determine the indirect tensile strength for brittle materials like concrete. It has been observed that the success of the test depends on the cracks initiation point position and therefore the arch loading angle; a crack appears in the center of the disk when the test is valid. To this effect, the main objective of this work was using Fast Lagrangian of Continua code FLAC2D; numerical analyses were performed to study the impact of the arch loading angle on the initial crack’s position in a 70 mm diameter Brazilian disk of concrete and mortar under loading arch 2α which varies from 5–45°. The distribution of stresses and the tensile strength at the center of the Brazilian disk obtained numerically was closely similar to analytical and experimental existing solutions. The results showed that to obtain a meaningful and validated test with the most accurate indirect tensile strength, it is recommended to take a loading arch 2α ≥ 20° for the concrete and 2α ≥ 10° for the mortar.

Griffith-based analysis of crack initiation location in a Brazilian test

“…Gutierrez-Moizant et al [11] conducted Brazilian tests in concrete with various contact angles and recommended using a loading arc of 20 • . Bouali and Bouassida [12] investigated the role of the contact angle for both concrete and mortar, concluding that 20 • was the most suitable contact angle for concrete while 10 • was recommended for mortar. Garcia-Fernandez et al [13] conducted Brazilian tests in PMMA samples, which enabled them to visualise the crack initiation process and demonstrated the important role of the contact angle.…”

“…Low contact angles lead to stress states that are close to the Hondros equations. However, this is not sufficient for the test to be valid as cracking can nucleate outside of the disk centre, as it is often reported when flat or large-radius jaws are used (see, e.g., [12,24,25]). While the maps presented in Section 4.2 provide a relationship between the critical load and the tensile strength (even if Eq.…”