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Studies of the source complex behaviour and of the ultrasound radiation of contact flexible multi-element transducers; Etudes du comportement complexe de source et du rayonnement ultrasonore des traducteurs multi-elements flexibles au contact

Abstract

This work deals with the ultrasonic nondestructive testing of parts with complex geometries using soft multi-element sensors. The different types of contact control configurations are presented first. Then, the difficulties encountered with conventional contact transducers are explained and the multi-element piezoelectric transducers technology, developed to meet these difficulties, is presented. The second chapter presents the results of finite-element calculations showing the complexity of a transducer in a condition of testing utilization. In a same configuration, the radiated far field calculated by finite-elements is compared to the measurement in order to validate the way the source behaviour is calculated. However, despite the efficiency of the finite-elements simulation, this tool is numerically too costly and cannot be used to optimize a full multi-element transducer. Therefore, a realistic source model is built and implemented in a radiation code based on high-frequency asymptotic approximations where only L and T volume waves are calculated. The incapacity of this model to reproduce the behaviour of T waves in some directions of propagation has led to give a particular attention to the fore-waves, neglected in the radiation calculation. Chapter 3 treats of the building of an exact radiation model taking into consideration the fore-waves contribution emitted by  More>>
Authors:
Publication Date:
Dec 15, 2007
Product Type:
Thesis/Dissertation
Report Number:
FRNC-TH-7610
Resource Relation:
Other Information: TH: These acoustique et vibrations; 45 refs.; Also available from Universite de Technologie de Compiegne, Centre Benjamin-Franklin, rue Roger-Couttolenc - BP 649, 60206 - COMPIEGNE Cedex (France)
Subject:
42 ENGINEERING; APPROXIMATIONS; COMPUTERIZED SIMULATION; FINITE ELEMENT METHOD; GREEN FUNCTION; INCIDENCE ANGLE; STRESS ANALYSIS; THREE-DIMENSIONAL CALCULATIONS; TRANSDUCERS; TWO-DIMENSIONAL CALCULATIONS; ULTRASONIC TESTING; ULTRASONIC WAVES; WAVE PROPAGATION
OSTI ID:
21154026
Research Organizations:
Universite de Technologie de Compiegne, 60 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR0900968032629
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
137 pages
Announcement Date:
May 18, 2009

Citation Formats

Amory, V. Studies of the source complex behaviour and of the ultrasound radiation of contact flexible multi-element transducers; Etudes du comportement complexe de source et du rayonnement ultrasonore des traducteurs multi-elements flexibles au contact. France: N. p., 2007. Web.
Amory, V. Studies of the source complex behaviour and of the ultrasound radiation of contact flexible multi-element transducers; Etudes du comportement complexe de source et du rayonnement ultrasonore des traducteurs multi-elements flexibles au contact. France.
Amory, V. 2007. "Studies of the source complex behaviour and of the ultrasound radiation of contact flexible multi-element transducers; Etudes du comportement complexe de source et du rayonnement ultrasonore des traducteurs multi-elements flexibles au contact." France.
@misc{etde_21154026,
title = {Studies of the source complex behaviour and of the ultrasound radiation of contact flexible multi-element transducers; Etudes du comportement complexe de source et du rayonnement ultrasonore des traducteurs multi-elements flexibles au contact}
author = {Amory, V}
abstractNote = {This work deals with the ultrasonic nondestructive testing of parts with complex geometries using soft multi-element sensors. The different types of contact control configurations are presented first. Then, the difficulties encountered with conventional contact transducers are explained and the multi-element piezoelectric transducers technology, developed to meet these difficulties, is presented. The second chapter presents the results of finite-element calculations showing the complexity of a transducer in a condition of testing utilization. In a same configuration, the radiated far field calculated by finite-elements is compared to the measurement in order to validate the way the source behaviour is calculated. However, despite the efficiency of the finite-elements simulation, this tool is numerically too costly and cannot be used to optimize a full multi-element transducer. Therefore, a realistic source model is built and implemented in a radiation code based on high-frequency asymptotic approximations where only L and T volume waves are calculated. The incapacity of this model to reproduce the behaviour of T waves in some directions of propagation has led to give a particular attention to the fore-waves, neglected in the radiation calculation. Chapter 3 treats of the building of an exact radiation model taking into consideration the fore-waves contribution emitted by a contact transducer exerting a random space-time distribution constraint at the surface of the considered medium. A radiation model, based on the calculation of exact Green functions of the Lamb problem is proposed. The exact model is particularly interesting in the case of sensor geometries with a long length with respect to other dimensions (2D case). Field calculation results are shown for an element of the matrix network (3D case) and for a linear element (2D case). A study of different existing approached models is carried out as well. The last chapter presents some results of the field radiated by a multi-element sensor as a whole, obtained with the exact radiation model. These results outline the importance of fore waves in the simulation of T waves testing using conformable multi-element transducers. (J.S.)}
place = {France}
year = {2007}
month = {Dec}
}