Eddy Current Testing (ECT) is a Non Destructive technique widely used in many industrial application fields in which it is very important to detect the presence of thin defects (generally called cracks) in conductive materials. Features of this technique are the cost-effective implementation and the kind of retrieved measured data that make possible estimating geometrical characteristics of a crack as position, length, width and depth. The analysis of these characteristics allows the user to accept or discard realized components then improving the production chain. To accomplish for this task some aspects have to be taken into account during the measurement process. They mainly concern with the realization of suitable measurement setup and post processing stages. As far as the measurement setup is concerned, crucial aspects are the choice of measurement and excitation devices. As for the former, in the past years the literature deeply explored many types of measurement probes highlighting advantages and disadvantages of different solutions. The choice of optimized excitation devices and strategies is now interesting recent studies about Non Destructive ECT (ND-ECT): together with common aspects as the amplitude and the frequency of the exciting signal, recently the attention has been paid to issues as the type of signal to be adopted. In particular it has been found as the use of complex excitation signals, meant as signals different from the sinusoidal ones and with wide frequency content, might raise eddy current responses trying to support the measurement, detection and characterization stages when “difficult cases” are explored (i.e. very short or annealed cracks). In this paper the authors propose an experimental comparison of different excitation signal designed to improve the quality of experimental data when difficult cases are experienced (such as annealed and small cracks) and consequently to obtain a more reliable extraction of defects geometrical features.

On the Use of Complex Excitation Sequences for Eddy Current Testing

BETTA, Giovanni;FERRIGNO, Luigi;LARACCA, Marco;
2013

Abstract

Eddy Current Testing (ECT) is a Non Destructive technique widely used in many industrial application fields in which it is very important to detect the presence of thin defects (generally called cracks) in conductive materials. Features of this technique are the cost-effective implementation and the kind of retrieved measured data that make possible estimating geometrical characteristics of a crack as position, length, width and depth. The analysis of these characteristics allows the user to accept or discard realized components then improving the production chain. To accomplish for this task some aspects have to be taken into account during the measurement process. They mainly concern with the realization of suitable measurement setup and post processing stages. As far as the measurement setup is concerned, crucial aspects are the choice of measurement and excitation devices. As for the former, in the past years the literature deeply explored many types of measurement probes highlighting advantages and disadvantages of different solutions. The choice of optimized excitation devices and strategies is now interesting recent studies about Non Destructive ECT (ND-ECT): together with common aspects as the amplitude and the frequency of the exciting signal, recently the attention has been paid to issues as the type of signal to be adopted. In particular it has been found as the use of complex excitation signals, meant as signals different from the sinusoidal ones and with wide frequency content, might raise eddy current responses trying to support the measurement, detection and characterization stages when “difficult cases” are explored (i.e. very short or annealed cracks). In this paper the authors propose an experimental comparison of different excitation signal designed to improve the quality of experimental data when difficult cases are experienced (such as annealed and small cracks) and consequently to obtain a more reliable extraction of defects geometrical features.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11580/28114
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