Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Fault detection in a thick structure by using the ISHM technique
Submission Author:
Fernanda Beatriz Aires de Freitas , RN , Brazil
Co-Authors:
Fernanda Beatriz Aires de Freitas, Larissa Pereira, Beatriz Marangoni, leandro stival, Valder Steffen Jr, Aldemir Ap Cavalini Jr
Presenter: Fernanda Beatriz Aires de Freitas
doi://10.26678/ABCM.COBEM2023.COB2023-0302
Abstract
Detecting and monitoring failures in mechanical systems is a matter of significant interest in industrial sectors. They are constantly searching for techniques capable of detecting incipient faults so that corrective actions can be taken in advance aiming to increase the machine's lifespan, reducing maintenance costs. The structural integrity monitoring technique based on electromechanical impedance (ISHM) is an interesting alternative since it involves non-destructive damage detection. In this methodology, piezoelectric transducers are positioned externally or incorporated into the structure to be monitored. The PZT patches simultaneously act as sensors and actuators. This behavior is possible due to the ability of piezoelectric materials to produce electric charges when subjected to mechanical deformations (sensor effect or direct piezoelectric effect) and to undergo mechanical deformations when subjected to an electrical potential (actuator effect or inverse piezoelectric effect). Therefore, it is possible to measure the electrical impedance of the PZT patches, which is directly related to the mechanical impedance of the structure. Structural stiffness, mass, or damping change directly affects the electrical impedance of the PZT patches due to the electromechanical coupling, indicating the presence of damage. Due to the efficiency of the ISHM technique for fault detection in slender structures, the present work is devoted to applying the electromechanical impedance approach in thick structures. For this purpose, two structures were monitored in the present work: a beam and a steel bar. Impedance signatures were measured at two distinct moments each, considering the healthy and faulty structures (a saw-cut was performed in the beam and a mass was added to the bar). The obtained impedance signatures from the healthy structure were used as a reference and compared with measured signatures at different times to evaluate the changes in the monitored structure caused by the damage. Such evaluation was performed using statistical indices (damage metrics) corresponding to scalar parameters representing the differences among the measured impedance functions. From the obtained results, it was demonstrated the possibility of monitoring the condition of the thick structure using the ISHM technique, as it was possible to identify the variations caused by the damage in the analyzed structure.
Keywords
ISHM, Damage Detection, thick structures
