Shear tests on joined materials

Results of an experimental investigation on brittle and non-brittle joining materials for ceramics tested in torsion will be presented and discussed. SiC hourglass shaped samples have been joined by glass-ceramics or by adhesives. The hourglass shape must be designed to minimize stress concentration and have shear stress only in the joined area. When the joining material is purely brittle (glass-ceramics), the shear strength is evaluated from the maximum of the torque/rotation curve. In the case of non purely brittle joining materials (adhesives) the joined area must be gradually reduced to a ring-shaped area until size independent results are obtained and the maximum of the torque/ rotation curve can be used to evaluate the shear strength. Modelling results help understanding the failure mode and therefore the meaning of the measured strength.