Development of fiber optic acoustic emission (AE) sensor for structural health monitoring in gas pipelines

• Main Author: Bay, Yong Wen
• Other Authors: Chan Chi Chiu
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/72126
• Institution: Nanyang Technological University

Deterioration of the steel pipeline systems may result in structure fatigue damage or crack. Early detection of damage can prevent any failures and ensure safe and continuous operation of the transmission gas pipelines. Structural health monitoring (SHM) methods are implemented to assess the condition of structures and achieve early detection of crack. The use of optical based acoustic emission (AE) sensor for SHM of pipeline is cost effective and offers many benefits such as the ability to simultaneous monitoring of several parameters, immunity to electromagnetic interference and corrosion resistance which make it suitable for continuous real time monitoring of gas pipeline. However, signal differentiation and damage identification are some challenges for optical based AE sensor. This project has proposed and developed an optical Fiber Bragg grating (FBG) system to monitor three different acoustic event that may occur in the gas pipeline - crack and impact like signals and gas leakage. The Phase-shifted fiber Bragg grating (PS-FBG) sensor used in this study has shown conclusive damage identification capabilities in detecting the AE signals generated by all three acoustic event. Furthermore, signal differentiation was also achieved by parameter and waveform based analysis of the recorded AE signals. It was observed that the crack like signal induce higher frequency order up till 400 kHz range while the impact like signal only in the range of 200 kHz. It is believed that these positive outcomes of the laboratory-based study on the optical FBG system can potentially be used for SHM in gas pipelines.