Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Monitoring of fatigue crack growth using a low-cost data acquisition device for impedance-based SHM considering dynamic measurements
Submission Author:
Diogo de Souza Rabelo , GO
Co-Authors:
Diogo de Souza Rabelo, Jared Hobeck, Daniel Inman, Roberto Mendes Finzi Neto, Valder Steffen Jr
Presenter: Diogo de Souza Rabelo
doi://10.26678/ABCM.DINAME2017.DIN17-0126
Abstract
A common problem in aircraft maintenance is the development of fatigue cracks in components located in areas of stress concentration. Although traditional nondestructive testing methods would be effective in inspecting cracks in an offline manner, real-time implementation of these methods is seldom accomplished. In this contribution, a procedure to monitor propagating cracks in aluminum beams undergoing dynamic cyclic loading is presented. A Piezoceramic (PZT) patch was attached to an aluminum sample to simultaneously excite the structure at a high-frequency range and monitor any changes in the structural mechanical impedance. To apply the fatigue load and induce fatigue crack, an electro-mechanical shaker was used. Proportional-Integral-Derivative (PID) controllers were used to change the shaker's drive frequency and drive acceleration in order to maintain the specimen under resonance in the first mode of vibration. During the vibrations, impedance measurements were acquired via the PZT patch by means of a low-cost impedance measuring device. Damage indexes were correlated with specific number of cycles until changes in drive frequency reached a critical limit. Finally, a statistical method is proposed to obtain the threshold for the Impedance-based Structural Health Monitoring (ISHM) system. The threshold is based on the knowledge of S/N curves and is compared with the damage indexes so that incipient damage could be detected before a visible crack could be observed in the specimen.
Keywords
Impedance-based Structural Health Monitoring, Fatigue crack, Threshold determination, crack threshold
