Abstract: In this study, the effect of the loading angle on the flattened Brazilian test is reviewed and the correction coefficient of the indirect tensile strength formula is summarized. Three dimensional finite element models for the flattened Brazilian disks are established to study the equivalent stress distribution by considering two kinds of loading angles. Based on the Griffith strength criterion, the equivalent stress distribution is affected by the loading angle in terms of stress distribution along loading diameter and flat ends. Moreover, the maximum equivalent stress occurs at edges of the flat ends in both two models. Three dimensional discrete element model is also constructed to study the initiation and propagation of cracks in the flattened Brazilian test. The micro-cracks first concentre at edges of the flat ends. However, macro-cracks, which will lead to the final failure of the specimen, initiate at the central disc. The results from the finite element method and discrete element method can be verified mutually. Compared with experiment phenomena, it is found that the precision of the two flat ends have a significant impact on the fracturing mode. The method of placing shims between the specimen and test machine is feasible to conduct the flattened Brazilian test conveniently.

Key words: the flattened Brazilian test, tensile strength, 3D finite element model, stress distribution, particle flow code