On the Removing Contact Problem of Brazilian Disc using Inclined Brackets; An Experimental Approach using Reflection

The influence of the contact between specimen and machine jaw in Brazilian Disc testing method is investigated by the reflection photoelasticity technique. To this end, six brackets with various angles from ۵° to ۳۰° are employed. A Polycarbonate plate cut by a water-jet cutting machine is employed as the reflection specimen. To figure out which contact is the best alternative for the flat one, stress distributions in contact with various angles under various applied forces are correlated. Results show only in contacts with ۵° angle the distributions of stresses remain completely similar to the usual Brazilian Disc. In the second step, polycarbonate specimens with various notch lengths from one-eighth of the disc diameter to half are tested. The distribution of stresses around notches resulting from photoelasticity fringes is similar to flat contacts only for contacts with ۵° slope. It is also notable that using inclined brackets the concentration of the stress at contacts dramatically declines to around half of the flat contacts.

کلیدواژه ها:

Brazilian Disc ، Stress Concentration ، Fracture Toughness ، Photoelasticity