Passive guided wave tomography for pipes inspection
Résumé
Structural Health Monitoring (SHM) consists in embedding sensors in a structure like aircraft fuselages, pipes or ship hulls in order to detect defects (for example cracks or corrosion in metallic materials or delamination in composite materials) before a serious damage occurs in the structure. Guided elastic waves emitted by a sensor and propagating to another one are often used as the physical way of detecting the defect. However, the implementation of SHM systems is restricted in many situations by the necessity to store or to harvest the electric energy necessary to emit the waves and also by the intrusiveness of the sensors. Guided wave tomography imaging is able to localize and quantify the severity of the defect when it comes to loss of thickness such as corrosion or erosion. However, it needs many sensors (generally piezoelectric-PZT-transducers) and it has a cost, particularly in terms of intrusiveness. Passive guided wave tomography, which uses ambient ultrasonic waves that are naturally present in the structure, is a promising method to design an SHM system with minimal power consumption and intrusiveness since no energy is required to emit the waves. In this paper the application of passive tomography to pipe inspection and comparison with classical "active" guided waves tomography approach are described.
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