Experimental validation of a characterization procedure for anisotropic materials using ultrasonic wave propagation techniques

Michel Darmon (1) , Benoit Mascaro (2) , Déborah Elbaz (3) , Nicolas Leymarie (1) , Philippe Guy (2) , Sylvain Chatillon (1)

1 LSMA (CEA, LIST) - Laboratoire Simulation et Modélisation Acoustique (CEA, LIST)
2 LVA - Laboratoire Vibrations Acoustique
3 EXTENDE

Non Destructive Evaluation (NDE) by ultrasonic testing (UT) is a common technique to ensure the structural integrity of safety-related components. The inspection of the various austenitic welds encountered on thick components of the primary circuit of nuclear reactors is very challenging. Austenitic welds are highly anisotropic and heterogeneous materials due to their dendritic structure produced by the cooling process during welding. Ultrasonic beam propagation through such a component may be greatly deviated, split and attenuated, depending on local grain orientation. A precise knowledge of these specific material properties is one of the key points to obtain reliable results with UT simulation codes and imaging tools. In this context, the characterization by ultrasonic wave propagation techniques of the anisotropy and damping in such media is of great interest. A measurement-based method has been previously developed to obtain in a non-destructive way the orthotropic tensor of the material and its orientation in the sample [1]. The used experimental device allows to carry out ultrasonic velocity measurements in transmission mode through a sample immersed in water for various 3D incidences; an optimization algorithm using both these measurements and a plane wave propagation model is then employed to evaluate the complex elastic constants of the material. In order to validate the complete characterization procedure i.e. both the measurement system and the inversion technique, the adopted strategy is to acquire experimental data on different materials, run the inversion routine to evaluate the orthotropic tensor of the material and its orientation and then compare experimental data to simulations performed using the inversed parameters. Simulations are computed using both a plane wave propagation model and the CIVA software beam simulation tool [2] which models the realistic and finite width beam radiated by the emitter. This experimental validation has been carried by steps on materials of gradual complexity: firstly on a non-attenuating isotropic material (aluminum), an attenuating isotropic material (Plexiglas) and an attenuating anisotropic steel with different disorientations of the crystal lattice in the sample frame. For all the tested materials the inversion-based simulations reproduce in their well-known validity range with a very good agreement the experimental signals concluding to a very satisfying validation of the characterization procedure.

Mots clés: Characterization; inversion algorithm; anisotropic materials; ultrasonic simulation

Domaines: Acoustique [physics.class-ph]; Matériaux; Modélisation et simulation

Michel Darmon, Benoit Mascaro, Déborah Elbaz, Nicolas Leymarie, Philippe Guy, et al.. Experimental validation of a characterization procedure for anisotropic materials using ultrasonic wave propagation techniques. 2019 International Congress on Ultrasonics, Oct 2019, Bruges, Belgium. ⟨hal-02317016⟩