Full Matrix Capture (FMC) approach is one of the advanced phased array methods wherein a single element is used in transmission and all the elements are used in reception. All elements are used as transmitters sequentially to obtain NxN numbers of A-scan signals for a probe with N elements. The raw A-scan signals are processed by Total Focusing Method (TFM). Conventional FMC-TFM has limitations in the inspection at large depth in highly attenuating materials due to single element transmission.

To improve the beam forming process, coherent recombination of the plane wave with specific angles is utilized in transmission and the same aperture is used for the reception in Plane Wave Imaging (PWI). A new methodology called Angle Beam Virtual Source FMC-TFM (ABVSFMC-TFM) is proposed to inspect the attenuating materials such as austenitic stainless steels and nickel base alloys. In this method, a set of few elements are used in transmission to focus the beam at a point near the sample surface called as a virtual source with the desired directivity and all the elements are used for receptions. The post processing is performed by Total Focusing Method (TFM). The ABVSFMC method leads to higher sensitivity than the conventional FMC due to increased energy during transmission using a few elements rather than a single element and improved divergence as compared to the PWI due to a small virtual source near the sample surface.

In the present paper, the FMC-TFM, PWI and ABVSFMC-TFM methods are compared for inspection of thick nickel based super-alloy (alloy 617) with slots at various depths in the range of 25 - 200 mm. The sensitivity and resolution achieved in the three methods are compared.


Total Focusing Method Based Ultrasonic Phased Array Imaging in Thick Structures

No proceedings papers in 2020. Video only.

QNDE2020 - Virtual Conference

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