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16th WCNDT 2004 - World Conference on NDT
CD-ROM Proceedings, Internet Version of ~600 Papers
Aug 30 - Sep 3, 2004 - Montreal, Canada
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SESSION: SIGNAL PROCESSING
ABSTRACT:
AN ANALYSIS OF ULTRASONIC WAVE PROPAGATION IN METALLIC PIPE STRUCTURES 
USING FINITE ELEMENT MODELLING TECHNIQUES 
A. Gachagan,1 P. Reynolds2 and A. Mcnab1.
1University Of Strathclyde, Glasgow, United Kingdom;  2Weidlinger Associates, Los Altos, CA, United 
States
 
 
 
This paper describes the development of a large finite element (FE) model representing ultrasonic inspection 
in a metallic pipe. The model was developed using PZFlex and comprises two wedge transducer 
components, water coupled onto the inner wall of a 36 inch diameter steel pipe. The 2MHz transducers are 
separated by 430mm and configured to generate/receive ultrasonic shear waves. One device is used in pulse-
echo mode to analyse any reflected components within the system, with the second transducer operating in a 
passive mode. Importantly, to minimise the models computational requirements, an external pressure 
loading function was applied to the wedge component within the model to simulate the transducer 
excitation. A number of simple defect representations have been incorporated into the model and both the 
reflected and transmitted ultrasonic wave components acquired at each wedge. Both regular slot and 
lamination defects have been investigated, at three different locations to evaluate the relationship between 
propagation path length and defect response. These defect responses are analysed in both the time and 
frequency domains and good correlation with experimentally measured waveforms is demonstrated. 
Moreover, the FE modelling has produced visual interpretation, in the form of a movie simulation, of the 
interaction between the propagating pressure wave and the defect. A combination of these visual aids and 
the predicted temporal/spectral waveforms has clearly demonstrated the essential differences in the response 
from either a slot or lamination defect. It should be noted that these modelled representations correspond to a 
propagation path length in excess of 150 wavelengths. Consequently, it was necessary to incorporate denser 
meshing within the FE model and run the simulations on a multi-processor SGI computer facility to produce 
accurate results.   
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MAIN AUTHOR:Anthony Gachagan, University Of Strathclyde, United Kingdom
Paper CODE: 287

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