Contrarily to the behaviour found in the material characterization tests conducted over plain round specimens, V-notched specimens exhibited a clear maximum in the torque versus twist angle curve prior to the failure of the specimen. This result can be surprising since because of the stress concentration induced by the notches, the response of these V-notched specimens was expected to be more brittle than the one found on the plain round specimens.In opinion of the authors, the reason behind this behaviour is the progressive release of energy resulting from the combination of the V-shaped notch plus the torsional loading. During the loading process, a first crack is initiated once the weakest point of the notch tip exceeds the strength of the material. However, since this crack forms 45 with the notch plane, crack propagation requires to create new crack surfaces on the V sides, moving away from the crack tip and increasing the amount of energy necessary for this crack to propagate. Therefore the propagation of this initial crack is only possible if the torque applied is increased what, in turn,induces the initiation of a new crack in a second weak point at the notch tip, which also can be propagated if the applied torque is increased. As a result, the applied torque increases while manycracks are initiated and partially propagated from the notch tip.The accumulation of cracks at the notch tip weakens the ligament of the specimen until it finally fails. Fig. 9 shows several pictures of the notch tip during and after one of the tests: the propagation of multiple cracks can be observed. In the case of the plain round specimens subjected to torsion for the mechanical characterization of the material, given the absence of the V-shaped notch, one single crack is propagated and therefore these specimens behave more brittle.