Skip to Main content Skip to Navigation
Theses

Caractérisation de défauts dans les milieux multi-diffusants : analyse de la méthode non linéaire d’interférométrie de la coda ultrasonore

Abstract : Coda waves are extremely sensitive to small disturbances of the propagation medium and therefore offer abundant information related to material damages. Recently, a method that combines Nonlinear acoustics and Coda Wave Interferometry (NCWI) has been proposed and applied to several types of materials (glass, mortar and concrete). In this thesis, numerical models (for homogeneous and heterogeneous medias ) are developed using the spectral element method to study the nonlinear acosutic effects highlighted by a pump wave of large amplitude and low frequency. Several parameters are related to the influence of the pump wave: the change of the elastic modulus and the quality factor within an area of Effective Damaged Zone (EDZ), the surface of the EDZ, the presence or absence of cracks within the EDZ, the change of the crack lengths and their number. The aim of numerical modeling is to be able to simulate ultrasonic coda waves in a multiple scattering medium with the presence of different types of non-linearities and to propose numerical models that are useful for the diagnosis and optimization of experimental set-ups. An experimental validation of laws linking damage parameters to NCWI observables is performed on a perforated aluminum plate. The nonlinear effects are caused by the contacts of the threads of a variable number of screws in the plate. NCWI allows the characterization and monitoring of different types of non-linearities: it perfectly answers the needs of Non Destructive Evaluation and Testing for early damage detection in complex materials.
Complete list of metadatas

Cited literature [188 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02881334
Contributor : Abes Star :  Contact
Submitted on : Thursday, June 25, 2020 - 3:54:12 PM
Last modification on : Friday, June 26, 2020 - 3:30:13 AM
Long-term archiving on: : Wednesday, September 23, 2020 - 5:05:40 PM

File

2019LEMA1004.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02881334, version 1

Citation

Guangzhi Chen. Caractérisation de défauts dans les milieux multi-diffusants : analyse de la méthode non linéaire d’interférométrie de la coda ultrasonore. Acoustique [physics.class-ph]. Université du Maine, 2019. Français. ⟨NNT : 2019LEMA1004⟩. ⟨tel-02881334⟩

Share

Metrics

Record views

59

Files downloads

29