Due to the difficulties associated with performing a direct uniaxial tensile test, the tensile strength of brittle materials is commonly estimated indirectly. The Brazilian test is probably the most widely accepted indirect technique among others. Since the development of the Brazilian test, the test has received considerable attention due to its ease of sample preparation and interpretation. However, the accuracy of this method has also been criticized for a long time in the literature. This paper aims to numerically study some of these criticisms by mainly focusing on failure mechanisms, the effect of contact loading conditions and stress distributions induced in the Brazilian test. Brazilian discs having contact angles ranging from 1 to 30° (i.e. concentrated to distributed loading scenarios) were simulated in the Fast Lagrangian Analysis of Continua (FLAC) based on the finite difference model. Results of this study show that at low contact loading angles, zones of high compressive stresses are generated at the vicinity of loading rims which is followed by an initiation and propagation of the cracks from these high-stressed zones. With an increase in the contact loading angle, the magnitude of compressive stresses at the vicinity of loading rims decreases leading to the disc's tensile rupture initiation at its centre. Also, it was found that the transition in the observed failure mode from cracking under the loading rims to central tensile cracking is material dependent in a Brazilian test. Finally, the ratio of uniaxial compressive strength to tensile strength was suggested as a controlling parameter for the evaluation of failure transition in a Brazilian test.
- Brazilian test
- Failure mechanism
- Tensile strength
- Transition contact loading angle