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 5° to 30° 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 5° 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 5° 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.

采用反射光弹性技术研究了巴西圆盘测试方法中试样与机爪接触的影响。为此，采用了 6 个角度从 5° 到 30° 的支架。采用水射流切割机切割的聚碳酸酯板作为反射样本。为了找出哪种接触是平面接触的最佳替代方案，需要将不同施加力下不同角度接触的应力分布相关联。结果显示，仅在 5° 角接触时，应力分布与通常的巴西盘完全相似。在第二步中，测试具有从圆盘直径的八分之一到一半的各种缺口长度的聚碳酸酯样本。仅对于具有 5° 斜率的接触，由光弹性条纹产生的凹口周围的应力分布与平面接触类似。还值得注意的是，使用倾斜支架，触点处的应力集中度急剧下降至平面触点的一半左右。