In this paper, a combined numerical and experimental study on the stress state of a fixing element from the rotor of a hydroaggregate is presented. The photoelastic and chromoplastic methods, together with finite elements analyses were used. The study is focused on the areas with stress concentration, zones where cracks may develop. These cracks may propagate, leading to the failure of the structure. The moment of crack initiation was determined experimentally, on chromoplastic models loaded until failure. Conclusions are drawn regarding the numerical validation of the experimental models and the possible brittle failure due to crack propagation.