Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide

To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide.

[1]  Steve Dixon,et al.  Weld defect detection using PPM EMAT generated shear horizontal ultrasound , 2015 .

[2]  P. Cawley,et al.  Ultrasonic isolation of buried pipes , 2016 .

[3]  S Dixon,et al.  Lift-off compensation for improved accuracy in ultrasonic lamb wave velocity measurements using electromagnetic acoustic transducers (EMATs). , 2006, Ultrasonics.

[4]  Koichi Mizutani,et al.  Conventional electromagnetic acoustic transducer development for optimum Lamb wave modes. , 2002, Ultrasonics.

[5]  Zenghua Liu,et al.  Longitudinal mode magnetostrictive patch transducer array employing a multi-splitting meander coil for pipe inspection , 2016 .

[6]  Makiko Kobayashi,et al.  Pipe inspection system of a pipe by three-modes guide wave using polarized-transverse wave EMATs , 2015 .

[7]  Riichi Murayama,et al.  Development of an ultrasonic inspection robot using an electromagnetic acoustic transducer for a Lamb wave and an SH-plate wave. , 2004, Ultrasonics.

[8]  Ray Kirby,et al.  A numerical model for the scattering of elastic waves from a non-axisymmetric defect in a pipe , 2015 .

[9]  Peter B. Nagy,et al.  Guided wave tomography of pipes with high-order helical modes , 2014 .

[10]  Frederic Cegla,et al.  High temperature ultrasonic crack monitoring using SH waves , 2011 .

[11]  P Cawley,et al.  High-temperature (>500°c) wall thickness monitoring using dry-coupled ultrasonic waveguide transducers , 2011, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[12]  Xinjun Wu,et al.  A Guided Wave Sensor Based on the Inverse Magnetostrictive Effect for Distinguishing Symmetric from Asymmetric Features in Pipes , 2015, Sensors.

[13]  Steve Dixon,et al.  Frequency dependent directivity of periodic permanent magnet electromagnetic acoustic transducers , 2014 .

[14]  Shi Yao-wu.  CALCULATION FOR LAMB WAVE DISPERSION CURVES , 2003 .

[15]  Steve Dixon,et al.  High temperature thickness measurements of stainless steel and low carbon steel using electromagnetic acoustic transducers , 2014 .

[16]  Hoon Sohn,et al.  Pipe Defect Visualization and Quantification Using Longitudinal Ultrasonic Modes , 2014 .

[17]  Anthony N. Sinclair,et al.  An NDT guided wave technique for the identification of corrosion defects at support locations , 2015 .

[18]  Wei Zhao,et al.  Study on the Lift-off Effect of EMAT , 2009 .

[19]  Masayuki Kobayashi,et al.  Ultrasonic Inspection System Using a Long Waveguide with an Acoustic Horn for High-Temperature Structure , 2014 .

[20]  Kenshi Matsumoto,et al.  Pipe Inspection System by Guide Wave Using a Long Distance Waveguide , 2015 .

[21]  M. Lowe,et al.  Defect detection in pipes using guided waves , 1998 .

[22]  Gui Yun Tian,et al.  Reduction of lift-off effects for pulsed eddy current NDT , 2005 .

[23]  Peter B. Nagy,et al.  Corrosion and erosion monitoring in plates and pipes using constant group velocity Lamb wave inspection. , 2014, Ultrasonics.

[24]  Francisco Hernandez-Valle,et al.  PRELIMINARY TESTS TO DESIGN AN EMAT WITH PULSED ELECTROMAGNET FOR HIGH TEMPERATURE , 2009 .

[25]  Francisco Hernandez-Valle,et al.  Initial tests for designing a high temperature EMAT with pulsed electromagnet , 2010 .

[26]  P A Petcher,et al.  Shear horizontal (SH) ultrasound wave propagation around smooth corners. , 2014, Ultrasonics.

[27]  Zujun Yu,et al.  A graphical method to solve a dispersion equation of Lamb wave: A graphical method to solve a dispersion equation of Lamb wave , 2013 .

[28]  Gui Yun Tian,et al.  An approach to reduce lift-off noise in pulsed eddy current nondestructive technology , 2014 .