Modélisation de la propagation et de la réception des ondes élastiques émises par un défaut sous contrainte. Application à la simulation des contrôles non destructifs par émission acoustique - Modeling of the propagation and reception of elastic waves emitted by a crack under stress. Application to the simulation of non-destructive testing by Acoustic Emission

TEL :: [tel-00860353, version 1] Modélisation de la propagation et de la réception des ondes élastiques émises par un défaut sous contrainte. Application à la simulation des contrôles non destructifs par émission acoustique

Modeling of the propagation and reception of elastic waves emitted by a crack under stress. Application to the simulation of non-destructive testing by Acoustic Emission

AE Non-destructive testing is used in many fields such as nuclear energy, oil and gas, civil engineering or mechanical engineering to check the integrity of structures under stress. Depending on the ratio of structure thickness to wavelength, the energy released by a crack under stress can propagate either as guided waves (in thin structures) or as Rayleigh wave (in thick structures). The analysis of signals resulting from this ultrasonic "passive" method is particularly difficult due to the complexity of typically measured signals. The objective of this thesis is to develop models to enable the simulation of AE testing experiments in the case of thick or thin structure. The developed models rely on the coupling between an AE source model, wave propagation models and an AE Sensor model. In the case of thick structures two 2D models (for plane and cylindrical surfaces) and a 3D model (for plane surface) have been developed to predict the signal corresponding to the Rayleigh wave emitted by a crack under stress. In the case of thin structures, a 2D model has been developed to predict the signal corresponding to the guided modes emitted by a crack under stress. Several parametric studies have been conducted to determine the influence of the different model input data on the AE signals and thus help to interpret AE testing results.