In the field of Structural Health Monitoring (SHM), active methods - which involve emitting a wave whose modification is studied when it encounters a fault - differ from passive methods, which require no prior wave emission. Researchers at List, a CEA Tech institute, have just developed a method based on the measurement and analysis of waves caused by the flow of a fluid in a pipe to detect possible defects.
The chosen solution is to use duos of Bragg grating coils on optical fibers, which function as elastic wave receivers. They have the advantage of being more resistant to extreme conditions (high temperatures, radiation) than the piezoelectric sensors traditionally used in active SHM. By processing the information from the sensor duos using a specially adapted tomography algorithm, the wall thickness profile can be reconstructed. This enables any defects to be detected, identified, located and measured.
The method has been tested and validated on artificial defects, and its effectiveness compared with that of a traditional active method. Successfully! Development of this method is continuing in partnership with EDF for use in industrial environments. Other applications are envisaged in aeronautics, for example.
Multi-function mass flow meters and controllers for gases
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