Fibre optic acoustic emission sensor system for hydrogen induced cold crack monitoring in welding applications

A fibre optic acoustic emission method to monitor hydrogen induced cold crack activities during welding is presented in this paper. A high sensitivity fiber Bragg grating (FBG) based acoustic emission (AE) measurement system is developed to monitor the cold crack induced AE events during a titanium aluminide alloy welding using gas tungsten arc welding method Frequency ranges of the AE where cold cracking occurs in the metal also has been evaluated. The measured frequency components of the AE events were within 270 kHz. The results of this feasibility study shows the potential of FBG based AE detection method to accurately predict the defects in welding, which will improve the quality of the final weld product in applications where higher welding standards are required.

[1]  Yu-Lung Lo.  In-fiber Bragg grating sensors using interferometric interrogations for passive quadrature signal processing , 1998, IEEE Photonics Technology Letters.

[2]  Cai Li,et al.  Ultrasonic Excitation and Fiber Bragg Grating Sensing Based on Wavelet Analysis , 2014 .

[3]  Quanbao Wang,et al.  Review on composite structural health monitoring based on fiber Bragg grating sensing principle , 2013 .

[4]  Rong-Sheng Lu,et al.  A Review of Optical NDT Technologies , 2011, Sensors.

[5]  Gangbing Song,et al.  Recent applications of fiber optic sensors to health monitoring in civil engineering , 2004 .

[6]  Orlando Frazão,et al.  Temperature field acquisition during gas metal arc welding using thermocouples, thermography and fibre Bragg grating sensors , 2007 .

[7]  Daining Fang,et al.  Study of fatigue crack characteristics by acoustic emission , 1995 .

[9]  S. Radic,et al.  Phase-shifted fiber Bragg gratings and their application for wavelength demultiplexing , 1994, IEEE Photonics Technology Letters.

[10]  Alfredo Güemes,et al.  Optical fibre sensors for monitoring of welding residual stresses , 2003 .

[11]  De-Shuang Huang,et al.  Noise reduction in lidar signal based on discrete wavelet transform , 2004 .

[12]  B. A. Barna,et al.  Determination of acoustic-emission sites using a digital nondestructive-evaluation workstation , 1988 .

[13]  Nobuo Takeda,et al.  Recent advancement in optical fiber sensing for aerospace composite structures , 2013 .

[14]  Khaled Daqrouq,et al.  ECG Signal Denoising By Wavelet Transform Thresholding , 2008 .

[15]  Raju,et al.  Acoustic emission techniques for failure characterisation in composite top-hat stiffeners , 2012 .

[16]  William W. Morey,et al.  IN-FIBER BRAGG-GRATING SENSORS , 1988 .

[17]  Sridhar Krishnaswamy,et al.  Theory and Applications of Laser Ultrasonic Techniques: Engineering and Biological Material Characterizati , 2003 .

[18]  Orlando Frazão,et al.  Study of strain-transfer of FBG sensors embedded in unidirectional composites , 2013 .

[19]  J. Barber,et al.  Acoustic emission investigation of cold cracking in gas metal-arc welding of AISI 4340 steel , 1995 .