Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling

Abstract

Ultrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA