FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas GeraisTrabalho de Conclusão de Curso (Graduação)Composite shafts have been showing promising results when applied to rotating machines due to its low weight/strength ratio and good fatigue resistance. Despite the advantages in comparison to more traditional materials, composites present different types of damage that are difficult to detect. Therefore, it is necessary to use monitoring techniques to detect incipient damages and prevent failure. So, this work evaluates the structural health monitoring method based on electromechanical impedance (ISHM) applied in a rotating machine with a composite shaft. This methodology uses the piezoelectric transducers bonded to the host structure as sensor and actuator to detect damage by monitoring changes in its electric impedance. Usually, the evaluation of the impedance responses is performed by applying damage metrics, which allows the quantification of the influence of damage. This is possible since the sensor’s electrical impedance is directly related to the mechanical impedance of the structure. For this investigation, two sensors (each one with four piezoelectric patches connected in parallel) were attached to the composite shaft. To simulate the damage condition, a nut was attached in different positions on the shaft. Also, in order to increase the robustness of the ISHM technique, the effects of the rotation speed of the rotor and temperature variation were evaluated. Additionally, a data normalization based on a hybrid optimization method associated with a given damage metric is used to minimize these influences
