Composición de imágenes ultrasónicas de alta resolución empleando sistemas de Phased Array para la inspección de componentes de uso nuclear
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Comisión Nacional de Energía Atómica. Instituto de Tecnología Sabato
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Tesis para optar al título de Magister en Ciencia y Tecnología de Materiales
The Phased Array Ultrasonic Technique (PAUT) has become in a widely used imaging tool for the Nondestructive Testing (NDT) in the industrial field, for example, for the periodic inspection of critical components of an installation. The PAUT allows to make deflections and focusing the ultrasound beam at different depths within the material, through an electronic control of each of the N elements that make up the array transducer. Thus, several electronic sweeps can be performed for obtaining images in different formats (B or S scans). The PAUT imaging is very efficient for detecting flaws whenever they have a favorable orientation to the beam direction. Therefore, it is necessary to establish the transducer position and setting the scanning correctly. Nevertheless, there are some drawbacks such as quality and intensity losses on the indications when the detection is made at high angles. For these reasons, it is necessary to perform amplitudes corrections and to explore from different positions using different angular ranges to obtain information with spatial diversity. This work presents the spatial and coherent compounding of PAUT images, which have been captured with different orientations and positions on the same plane of the piece, to be combined in a single image. Each of the individual primary images provides specific spatial information that depends on the emission characteristics, so that the combination allows all the information to be presented in a higher quality image in which the defect detection capacity is increased. A generic algorithm was developed for performing a scanning conversion using the bilinear interpolation, which allows obtaining a high quality final image and more accuracy in the quantitative analysis of indications. The proposal has been validated on materials and components of nuclear applications.
The Phased Array Ultrasonic Technique (PAUT) has become in a widely used imaging tool for the Nondestructive Testing (NDT) in the industrial field, for example, for the periodic inspection of critical components of an installation. The PAUT allows to make deflections and focusing the ultrasound beam at different depths within the material, through an electronic control of each of the N elements that make up the array transducer. Thus, several electronic sweeps can be performed for obtaining images in different formats (B or S scans). The PAUT imaging is very efficient for detecting flaws whenever they have a favorable orientation to the beam direction. Therefore, it is necessary to establish the transducer position and setting the scanning correctly. Nevertheless, there are some drawbacks such as quality and intensity losses on the indications when the detection is made at high angles. For these reasons, it is necessary to perform amplitudes corrections and to explore from different positions using different angular ranges to obtain information with spatial diversity. This work presents the spatial and coherent compounding of PAUT images, which have been captured with different orientations and positions on the same plane of the piece, to be combined in a single image. Each of the individual primary images provides specific spatial information that depends on the emission characteristics, so that the combination allows all the information to be presented in a higher quality image in which the defect detection capacity is increased. A generic algorithm was developed for performing a scanning conversion using the bilinear interpolation, which allows obtaining a high quality final image and more accuracy in the quantitative analysis of indications. The proposal has been validated on materials and components of nuclear applications.