Commissariat a L'energie Atomique Et Aux Energies Alternatives

Commissariat a L'energie Atomique

Thierry Sollier

Claude Fermon

Jean-Marc Decitre

Myriam Pannetier

Nicolas Biziere

Francois Vacher

François Vacher

The invention concerns a method for producing an assembly of at least one transmission coil (B) and one reception coil (B) for eddy current testing, the reception coil receiving in the absence of fault a complex amplitude signal V, subject to a variation &#x3b4;Vin the presence of a characteristic fault to be detected. The method consists in selecting the distance &#x394;between the axes of the transmission coil and the reception coil so as to maximize the ratio I&#x3b4;V/VI.

Method for assembling a high-dynamic and high-spatial resolution eddy current testing head

A device for non destructive evaluation of defects in a metallic object () by eddy currents, comprises a field emitter () for emitting an alternating electromagnetic field at a first frequency fi in the neighborhood of the metallic object (), and a magnetoresistive sensor () for detecting a response signal constituted by a return electromagnetic field which is re-emitted by eddy currents induced by the alternating electromagnetic field in the metallic object (). The device further comprises: a driving circuit () for driving the magnetoresistive sensor () by a current at a second frequency fc which is different from the first frequency fi, so that the magnetoresistive sensor () acts as an in situ modulator; a detector for detecting a response signal between the terminals of the magnetoresistive sensor (); a filter for filtering the response signal detected by the magnetoresistive sensor () to keep either the frequency sum (fi+fc) of the first and second frequencies or the frequency difference (fi&#x2212;fc) of the first and second frequencies, and a processor for processing the filtered response signal and extract eddy current information on defects in the metallic object ().

Method and device for non destructive evaluation of defects in a metallic object

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Antony, France

Thierry Sollier