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EBSD image based fem simulation of ultrasonic wave propagation in dissimilar metal welds

 
: Lee, K.; Han, T.; Schubert, F.; Höhn, S.

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Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren -IZFP-, Institutsteil Dresden:
7th International Workshop NDT in Progress. Online Proceedings : NDT of Lightweight Materials. Dresden, Germany, November 7 - 8, 2013
Online im WWW, 2013
http://www.ndt.net/search/docs.php3?MainSource=168
2 pp.
International Workshop "NDT in Progress" <7, 2013, Dresden>
English
Conference Paper, Electronic Publication
Fraunhofer IZFP, Institutsteil Dresden ( IKTS-MD) ()
Fraunhofer IKTS ()

Abstract
Analysis of the ultrasonic testing (UT) in dissimilar metal welds (DMWs) is complicated due to acoustic anisotropy and local heterogeneity so that the ultrasonic wave is propagated along crystallographic directions as well as it is scattered by randomized weld boundaries. With the idea, development of a straightforward numerical modelling technique to predict ultrasonic wave propagation in weld boundaries and local heterogeneities has been necessary for reliable UT technique's usages in nondestructive testing (NDT). In this study, application of electron backscatter diffraction (EBSD) was considered to obtain detail information about locally major crystallographic directions and grain boundaries. In order to analyse EBSD results, grain orientation density functions were used by MATLAB program since it provides distribution of major crystallographic orientation. And using digital image processing was considered to obtain grain boundaries of major misorientation in comput er graphics. Due to limitation of measurement on the whole regions of DMWs in this study, similarity between results of digital image processing at same sectional sample's EBSD image and chemical etching metallography image was reviewed and approximate similarities were consequently deducted. With similarities, FEM modelling contained the whole regions of DMW was implemented by using digital image processing. Simulation of the image based FEM model with ultrasonic phased array technique was implemented by using explicit dynamics FEM technique in commercial LS-DYNA FEM package. Results of ultrasonic wave propagation's simulation in dissimilar metal welds were reviewed and verification of the simulation was conducted by comparison with analytical methods (phase velocity surface, slowness velocity) and laser Doppler vibrometer (LDVT) measurement for scanning of physical non-contact vibration on the surface.

: http://publica.fraunhofer.de/documents/N-441799.html