FREQUENTIAL REFLECTOMETRY (FDR) APPLIED TO THE NON-DESTRUCTIVE EVALUATION OF EXTERIOR PRESSURE DUCTS

Abstract

This paper presents an electromagnetic method ofdiagnosis based on frequency domain reflectometry (FDR)associated with an inversion algorithm developed byINRIA, ISTL™(Inverse Scattering for TransmissionLines). ISTL™allows estimating the spatial profile of theelectrical impedance of the line from the FDRmeasurements. Experimental results on two mockups ofexternal post-tensioned ducts with filling defects show thefeasibility of the method. We will try to show thesimilarities between auscultation external post-tensionedducts and measurement of water content by TDR probes(Time Domain Reflectometry