Abstract
We developed an advanced optical fiber Acoustic Emission (AE) monitoring system with a phase compensation feed back circuit. Two lasers transmitted through the reference and sensing arms are combined by a 2x2 coupler and detected by two photodiodes as the intensity change of the interfered laser. Outputs of the photodiodes are then combined in a differential amplifier which extracts error signal and improves the S/N ratio. The developed system was demonstrated to detect weak guided wave AE signals such as zero-th order longitudinal cylindrical wave (Lo-mode) with the S/N ratio higher than that of PZT sensor. This system was utilized to monitor the oxidation resistance of various alloys during thermal cycles from 300 K to 1273 K. We detected weak AE signals from micro fractures of growing oxide films of boiler tube and austenitic stainless steel, but no AE from Inconel 600 tubes. Here the optical fiber sensor was wound over the tube at 600 K. Both the AE counts and amplitudes during thermal cycles showed clear tendency depending on the oxidation resistances of the alloys.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
