The distributions of the principal tensile stress in orthotropic Brazilian Disk were shown under a pair of concentrated forces and compared with those by Claesson in previous author’s work. It was observed that the stress distributions are influenced by the angle of the disk’s orientation and the ratio of the elastic moduli. In this paper, the distributions of the principal tensile stress that is generated in the Brazilian disk are shown for several contact areas between the specimen and loading plates under the diametrical compression test. In this study, the load on the specimen is assumed as uniform distributed stress. The distributions of principal tensile stresses are obtained by calculation using Lekhnitskii’s theoretical solution and the equation that was added by authors. Calculations to obtain the principal tensile stresses are carried out under several orientations of disk. Graphical representations show that the tensile stress that is generated near the loading plates decreases as the contact area between the specimen and loading plates increases. On the other hand, the tensile stress generated at the center of disk decreases by only a small amount as the contact area increases.
The diametrical compression test is a simple and relatively inexpensive test for measuring the tensile strength of brittle material. This test is performed by placing a disk between two (rigid) plates and applying a diametrical compressive load. The test induces a biaxial stress state in which the stress at a center of the disk is compressive in the x-direction ( s x), and tensile in the y direction ( s y). Theoretically, for an isotropic material, the tensile stress reaches a maximum at a constant magnitude of P/(pa), where P represents the applied load and a represents the radius of the disk [1,2].