Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
ACOUSTIC EMISSION SYSTEM APPLIED TO THE IDENTIFICATION OF EARLY STAGE CRACKS IN METALLIC COMPONENTS
Submission Author:
Raul Gaspari Santos , SP
Co-Authors:
Raul Gaspari Santos, Niederauer Mastelari
Presenter: Raul Gaspari Santos
doi://10.26678/ABCM.COBEM2023.COB2023-2158
Abstract
Components of machines and service equipment that are subjected to mechanical stress are subject to failure due to permanent deformation or fracture. In the case of fractures, the initial stage will always be characterized by the nucleation of small cracks that will meet to form a main crack that will propagate until the component ruptures. The identification of these micro cracks can represent an increase in reliability, safety and a reduction in risks linked to equipment downtime. The so-called Acoustic Emission (AE) sensor, combined with different signal analysis techniques, can be used in the predictive maintenance routine of these mechanical components in order to identify these cracks at an early stage. Based on the above, the present work proposes the construction of a system, with low production cost, composed of an AE sensor using piezoelectric diaphragms of the PZT type (Lead Zirconate Titanate), data acquisition system (DAQ) and techniques analysis of signals such as Fourier Transform, Wavelets, counting of events and calculation of signal energy, to identify cracks caused by small deformations that will lead to failure by fracture of the material. An experimental validation bench was created for the development stages, which allowed the validation of the equipment for use in low-cycle tensile and fatigue tests in a dynamic testing machine. The data presented show that the system was able to identify cracks in the material in its initial stage, reaching the main objective of the work. By analyzing the frequency spectrum of the signal, it was possible to identify frequency patterns between 0 and 20 kHz corresponding to crack formation or propagation events. The frequency spectrum over time (Wavelet) showed that these low frequency signals always occurred when events were recorded and that higher frequency signals, around 50 kHz, are linked to these events. It was also noted that the energy of the signal increases significantly when there are more events, if we compare signs of deformation of the specimen with signs of fracture of the specimen, showing that the deformation of the specimen is linked to the formation of micro cracks.
Keywords
Acoustic Emission Technique, Structural Health Monitoring (SHM), Data acquisition, Data analysis
