Advanced ultrasonic array techniques such as full matrix acquisitions provide considerable amount of data making possible by the use of suitable processing algorithms enhanced capability of defects imaging and therefore improved localization and sizing. In general the applied processing consists in a coherent summation of signals (synthetic focusing) based on a time of flight inverse matching. Such algorithms have been connected to forwards models allowing to image defects in realistically complex configurations. In this communication we present results obtained on defects detected through complex surfaces on defects detected by multiple ultrasonic paths (tip diffraction, corner effect, mode conversions). The performances of the technique are evaluated both on simulated and experimental results.
Beyond the detection of defects, their characterization (identification, positioning, sizing) is one goal of great importance often assigned to the analysis of NDT data. The first step of such analysis in the case of ultrasonic testing amounts to image in the part the detected echoes. This operation is in general achieved by considering time of flights and by applying simplified algorithms which are often valid only on canonical situations. In this communication we present an overview of different imaging techniques studied at CEA LIST and based on the exploitation of direct models which enable to address complex configurations and are available in the CIVA software plat-form. We discuss in particular raymodel based algorithms, algorithms derived from classical synthetic focusing and processing of the full inter-element matrix (MUSIC algorithm).
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Context and motivationCase study: ECT inspection of an Aluminum plate containing notches Intensive simulation by means of surrogate models
Estimation of hit-miss ratios and calculation of POD curves by regressionConclusions and perspectives
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