Computational Verification of the Optimum Boundary Condition of the Brazilian Tensile Test

The present research analyses the configuration of jaws to avoid the premature failure of the disc in the Brazilian test. The objective is to depict the loading device configuration that most likely produces results comparable to the Hondros' analytical stress solution. To this end, several numerical analyses have been carried out for different contact angles with the finite element method. It was deduced that the final contact angle plays an important part in the success of the Brazilian test and that the Griffith criterion can be fulfilled if the equivalent stress is calculated. Additionally, the orientation of the forces in the contact between the loading device and the disc has been studied for different friction conditions. According to the numerical results, it was found that a loading arc configuration of 20 degrees shows the best agreement with the probable values given by the analytical stress model when the uncertainty of its magnitudes is taken into account. The study also demonstrates that the friction in the contact between the optimal loading configuration and the disc does not seem to significantly affect the theoretical predictions in the centre of the disc.