title: Validation of a thermal bias control technique for Coda Wave Interferometry (CWI).
abstract: The Coda Wave Interferometry (CWI) analysis serves to monitor the variation of propagation velocity in a heterogeneous medium with high precision (10(-3)% in relative terms). In combination with acoustoelastic theory, this type of analysis offers an NDT method for stress evaluation and/or damage detection. Since the CWI method is intended to evaluate extreme levels of accuracy, the presence of bias under certain circumstances can undermine evaluation results and/or test repeatability. In this paper, we offer a bias control technique involving the use of a second (reference) specimen for CWI analysis that is designed to compensate: (1) the thermally-induced velocity variation due to environmental temperature fluctuations; and (2) bias originating from experimental procedures. The presentation of this technique contains both a theoretical analysis and experimental protocol for the purpose of implementation. Furthermore, comparisons of experimental results have been included in order to demonstrate the utility of this bias control technique under laboratory conditions.
authors.affiliation: LUNAM Université, IFSTTAR, MACS, CS4, F-44344 Bouguenais Cedex, France. yuxiang.zhang@ifsttar.fr
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Odile
authors.initials: O
authors.lastname: Abraham
authors.forename: Vincent
authors.initials: V
authors.lastname: Tournat
authors.forename: Alain
authors.initials: A
authors.lastname: Le Duff
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lascoup
authors.forename: Ahmed
authors.initials: A
authors.lastname: Loukili
authors.forename: Frédéric
authors.initials: F
authors.lastname: Grondin
authors.forename: Olivier
authors.initials: O
authors.lastname: Durand