Numerical modeling of Nonlinear Coda Wave Interferometry in a multiple scattering medium with a localized micro-cracked zone

Speaker:
CHEN, Guangzhi; IFSTTAR Departement Geotechnique environnement risques naturels et sciences de la terre; France

Authors:
Chen, G.; LUNAM University; France
Pageot, D.; LUNAM University; France
Legland, J.-B.; IFSTTAR; France
Abraham, O.; IFSTTAR; France
Chekroun, M.; LUNAM University; France
Tournat, V.; LUNAM University; France

ID: ECNDT-0200-2018
Download: PDF
Session: Nonlinear Ultrasonics 3
Room: G2
Date: 2018-06-14
Time: 09:00 - 09:20

The spectral element method is used to perform a parametric sensitivity study of the Nonlinear Coda Wave Interferometry (NCWI) method in a heterogeneous sample with a localized micro-cracked zone (1). The influence of a strong pump wave on localized nonlinear damage has been modeled as modifications of the elastic properties in an Effective Damage Zone (EDZ), depending on the pump wave amplitude. To match the previous experimental results of Zhang et al. (2), the corresponding change of the attenuation coefficient has to increase of 700%, which is unexpectedly high. To mitigate this effect and to be closer to real defects, random cracks of random orientations are added to the EDZ. The results demonstrate that the variation of elastic properties required to match the experimental results are reduced. The numerical results reported constitute another step towards quantification and forecasting of the nonlinear acoustic response of a cracked material, which proves to be necessary for quantitative non-destructive evaluation.