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- Englisch (13) (entfernen)
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- Ray tracing (5)
- Anisotropy (3)
- Austenitic weld (3)
- SAFT (3)
- Austenitic weld material (2)
- Austenitic welds (2)
- Critical angle (2)
- Directivity (2)
- Energy flux vector (2)
- Energy skewing (2)
In this contribution a simulation tool is developed to compute the energy skewing angles and energy coefficients
for the reflected and refracted plane waves in following general cases: (1) reflection and refraction
of plane elastic waves at an interface between isotropic and transversely isotropic solid, (2) reflection
and refraction of plane elastic waves at an interface between transversely isotropic and isotropic solid, (3)
reflection and refraction of plane elastic waves at an interface between two general transversely isotropic
solid and (4) reflection of plane elastic waves from a stress free boundary of a transversely isotropic solid.
Computational results for analytically evaluated acoustic wave energy skewing angles and energy reflection
and transmission coefficients in acoustically anisotropic materials such as austenitic steel materials
exhibiting columnar grain orientation are presented. The obtained results show that the acoustic energy
skewing angles and coefficients in austenitic steel materials strongly depend upon the columnar grain
orientation and are less influenced by the grain orientations which are parallel and perpendicular to the
interface.
Ultrasonic examination of anisotropic inhomogeneous austenitic welds is challenging, because of the columnar grain structure of the weld leads to beam skewing and splitting. Modeling tools play an important role in understanding the ultrasound field propagation and optimization of experimental parameters during the ultrasonic testing of austenitic welds as well as the interpretation of the test results. In this contribution, an efficient theoretical model based on the ray tracing concepts is developed to calculate the ultrasonic fields in inhomogeneous austenitic welds quantitatively. The developed model determines the ultrasound fields by taking into account the directivity of the ray source, the inhomogenity of the weld as well as ray transmission coefficients. Directivity of the ray source in columnar grained austenitic materials (including layback orientation) is obtained in three dimensions based on Lamb's reciprocity theorem. Ray energy reflection and transmission coefficients at an interface between two general columnar grained austenitic materials are calculated in three dimensions. The ray tracing model predictions on inhomogeneous austenitic weld material are compared against those from CIVA, a commercial non-destructive modeling and simulation tool. The ultrasonic modeling tools in CIVA are based on semi-analytical solutions. For beam propagation simulation, a so-called 'pencil method' is used, which involves modeling the probe as a set of individual source points, each radiating 'a bundle' of diverging rays into the medium and integrating those elementary contributions. Inhomogenity in the weld region is approximated by mapping the grain orientations on weld macrograph. Simulation results for ultrasonic field profiles for an austenitic weld are shown to be in good agreement with the corresponding experimental results.
In this contribution a 3D ray tracing model for ultrasonic
field evaluation in inhomogeneous anisotropic materials
such as austenitic welds is presented. The inhomogenity of
austenitic weld material is represented as several
homogeneous layers. The general problem of energy
reflection and transmission at the boundaries of the layers
are solved resulting 3D amplitude and energy reflection and
transmission coefficients. The directivity factor for the ray in
general arbitrary oriented austenitic weld material (including
lay back orientation) is determined based on Lambs
reciprocity theorem. The transducer excited ultrasonic fields
are accurately evaluated by employing ray directivity factor,
transmission coefficients, divergence of the ray bundle and
density of rays. Finally, the comparison between theoretical
and experimental results will be described.