Note: This english version is not equal to the German conference paper: ULIAS: Computergestützte quantitative Ultraschallprüfung German
Nondestructive testing (NDT) with ultrasound of isotropic as well as anisotropic materials is based on acoustic (scalar) and elastic wave propagation, scattering and diffraction. For computational modeling of real NDT situations we developed two numerical codes, which are called the Acoustic Finite Integration Technique (AFIT) and the Elastodynamic Finite Integration Technique (EFIT). AFIT models acoustic waves in air and fluids and EFIT models elastic waves in isotropic and anisotropic solids. The materials can be arbitrarily inhomogeneous and dissipative (viscid).
These numerical codes provide not only a deep fundamental physical understanding of ultrasound in realistic environments, they can also serve as tools to obtain synthetic data to be used as input data for acoustic or elastic imaging algorithms, either as a testbed or to verify experimental results. As imaging algorithms B-scan and SAFT (Synthetic Aperture Focusing Technique) as well as inverse scattering based diffraction tomography schemes are available. The combination of the numerical modeling codes AFIT and EFIT with imaging algorithms like SAFT on the same computer is the basis of Computer Aided Inspection (CAI). The modeling codes AFIT and EFIT have been applied to various NDT situations. Some examples comprise the NDT of surface or backwall breaking cracks in isotropic steel and transversely isotropic austenitic steel, the air-coupled or fluid-coupled NDT of gas or oil pipelines, and the NDT of concrete. Typical outputs of these codes are time snapshots of the wave field and A-scans. The latter can be compared with measured data. A sequence of the time snapshots can be used to generate wavefront movies in MPEG format, which can be run by an MPEG player software under UNIX or MS-DOS. These wavefront movies are very helpful by the interpretation of the modeled or measured A-scans. To include the ultrasonic transducer itself in the NDT model, the Finite Integration Technique has been applied to the governing equations of piezoelectric waves. This additional numerical tool is called PFIT, this is the acronym of the Piezoelectric Finite Integration Technique. Now the whole NDT situation can be modeled by the combination of PFIT, AFIT and/or EFIT. The power of these NDT tools will be demonstrated in some particular cases.
R. Marklein, K. J. Langenberg, S. Klaholz, R. Baermann, K. Mayer Dept. of Electrical
Engineering, FB 16, University of Kassel D-34109 Kassel, Germany
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Kurzfassungen der Vorträge und Plakatbeiträge der ZfP Jahrestagung 1996.
Hier der Bericht über die Jahrestagung or Conference Report in English.
Volltext-Bezugsquelle: DGZfP Berlin Email: 100335,3315@compuserve.com
Sprache:Deutsch
Rolf Diederichs 1. August1996, info@ndt.net