Session: 05-01: Guided Waves I

Paper Number: 134683

134683 - Passive Ultrasonic Guided Waves Acquisition Using Electro Magnetic Acoustic Transducers (EMATs): Design and Experimental Validation 

Abstract: 

As downtimes have a major economical impact in many industrial sectors, reducing them by enabling faster inspections and earlier detection of damage is of utmost importance. Ultrasonic guided waves enable the inspection of large areas at once with only a small number of sensors due to their large propagation distance with a high sensitivity to defects. However, their multimodal and dispersive behavior leads to complex data if no specific sensors or sensor network is used to filter the various components of the signal. For this purpose, the use of Electro Magnetic Acoustic Transducers (EMATs) offers a promising instrumentation solution, as their design can be tailored to a large range of directivity and modal requirements without relying on a large network of sensors. However, actuation using such sensors is still a challenge as it needs high voltage leading to risks and requiring specific electronics and a large energy consumption. In this context, EMATs appear to be good candidates for passive guided waves applications. These techniques rely on the measurement of the ambient noise inherent [RA1] to the function of the structure, such as air or liquid flow for instance. This way, sensors are used only for reception, and equivalent signals to the ones acquired with a sensor acting as an actuator are later reconstructed using signal processing tools. In this study, we design and test EMATs with various coil geometries, and analyze their influence on modal selectivity and directivity. Experimental tests are carried out, using a thin piezoelectric disc for wave generation at first, validating the properties of the receiving EMATs, and then with an air stream as the only excitation source for the full passive configuration. The influence of the coil design on the proper recovery of the ultrasonic signals from the ambient noise but also directivity, modal selectivity and overall sensitivity is discussed. Such sensors coupled with passive techniques could be embedded in structures, enabling their Structural Health Monitoring (SHM).

Presenting Author: Raphaël Carpine CEA

Presenting Author Biography: Raphaël Carpine is a researcher in the field of Ultrasonic Guided Waves, applied to Structural Health Monitoring. He also has a background in Operational Modal Analysis, signal processing using Continuous Wavelet Transform and nonlinear dynamics.

Authors:

Raphaël Carpine Université Paris-Saclay, CEA, List
Arnaud Recoquillay Université Paris-Saclay, CEA, List
Julien Albertini Université Paris-Saclay, CEA, List