Joint Workshop of Russian Acoustical Society (RAS) and French Acoustical Society (SFA) “High Intensity Acoustic Waves in Modern Technological and Medical Applications”, 14-15 November, 2005. Moscow 120 T.Goursolle 1 , S. Dos Santos 1 ,F. Vander Meulen 1 , L. Haumesser 1 and O. Bou Matar 2 ULTRASONIC PARAMETRIC IMAGING OF METALLIC SAMPLES USING NONLINEAR ACOUSTIC MEASUREMENTS 1 Laboratoire d’Ultrasons Signaux et Instrumentation de L’Université François Rabelais / GIP Ultrasons, FRE2448 CNRS, EIVL, Rue de la Chocolaterie BP 3410, 41034 Blois Cedex, France Tel: +33 (0) 2 54 55 84 40; Fax: +33 (0) 2 54 55 84 45 E-mail: thomas.goursolle@univ-tours.fr 2 IEMN UMR8520 CNRS, Cité Scientifique - Avenue Poincaré, BP 69 59652 Villeneuve d'Ascq Cedex – France Tel: +33 (0) 3 20 19 79 49 A calibrated contact phase modulation method [1] have been developed in the laboratory. Nonlinear effects coming from parametric interaction of an high and a low frequency waves can be measured as a phase modulation of the HF acoustic beam. According to the NDE needs, the nonlinearity in samples with interfaces, coming from aeronautic industries (two layers of aluminum bonded by an epoxy thin layer), must be measured. In order to meet these needs, our method has been extended. Thanks to additional measurements of reflection coefficient, calibration procedure, based on the self- reciprocity principle applied to the LF transducer, has led us to obtain absolute value of the LF particle velocity at the bonded interface. To know the feasibility of this extension, preliminary results of nonlinear parameter have been obtained in bi-layer samples considering the propagation inside the layer only. An image have been created by slope values of phase modulation obtained from 25 regularly spaced measurements. 1. Introduction In this work, according to the needs of NDE in aeronautic industry, we propose to extend a phase modulation method [1] to samples having high impedance mismatch between two layered samples manufactured by CDE Dassault Aviation (two layers of aluminum bonded by an epoxy thin layer). This in-situ method and associate calibration procedure was previously validated in homogenous media (fluids, fused silica, aluminum). Two kinds of sticking are analysed: an healthy adhesive epoxy layer which is completely polymerized between two pieces of aluminum (E2) and a damaged one whose polymerization was interrupted during the process (F2). For the measurement in homogenous media [1], parametric interaction is achieved between the HF wave which is reflected from the edge of the sample and the LF wave which is emitted at this edge during the HF wave reflection. With bonded aluminum samples, new aspects have enhanced the difficulty: - What is the influence of the adhesive epoxy layer on the HF wave propagation through the sample? - How can the LF transducer be calibrated? In this work, the feasibility of our measurement in these samples is investigated, and in particular the LF particle velocity on adhesive epoxy interface and the phase modulation of the HF wave which is reflected on this interface are studied.