A Photoelastic Study of T-stress in Centrally Cracked Brazilian Disc Specimen Under Mode II Loading

In the traditional formulation of the stress field near a crack tip, the presence of the T-stress is generally considered only under mode I or mixed mode I and II conditions. In this paper its presence in almost pure Mode II is experimentally investigated by mean of photoelasticity and its effects on the isochromatic fringe patterns are discussed. The test specimens are Brazilian discs containing sharp central cracks. After crack generation, all residual stresses are removed with thermal treatment of the specimens. Then, a compressive load is applied in a specific angle to induce mode II deformation. The observed isochromatic fringes show very good consistency with theoretical predictions. Experimental results indicate that this specimen has a negative T-stress in mode II condition. The results calculated for K(II) and T from photoelastic experiments agree well with numerical results available from finite element method.