Passive guided wave tomography for structural health monitoring

Abstract : In this paper is presented a baseline-free quantitative method for imaging corrosion flaws in thin plates. It only requires an embedded guided wave sensor network used in a fully passive way, i.e. without active emission of waves. This method is called passive guided waves to-mography. The aim of this development is the use of this method for the Structural Health Monitoring (SHM) of critical structures with heavy limitations on both sensor's intrusiveness and diagnostic's reliability because it allows to use sensors that cannot emit elastic waves such as Fiber Bragg Gratings (FBGs) which are less intrusive than piezoelectric transducers (PZTs). The idea consists in using passive methods in order to retrieve the impulse response from elastic diffuse fields-naturally present in structures-measured simultaneously between the sensors. In this paper, two passive methods are studied: the ambient noise cross-correlation and the passive inverse filter. Once all the impulse responses between the sensors are retrieved, they are used as input data to perform guided wave tomography.