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SHM of pipes using torsional waves generated by in situ magnetostrictive tapes
Elankumaran Kannan, Bruce W. Maxfield,
Published in
2007
Volume: 16
   
Issue: 6
Pages: 2505 - 2515
Abstract
Long-range, torsional guided waves generated in pipes using magnetostrictive sensors (MsSs) have great potential for applications to the structural health monitoring (SHM) of hard-to-inspect pipes. This paper reports an improved MsS technique (when compared to related techniques currently used for the NDT of pipes) that uses polymeric magnetic tape material that is suitable for use in a variety of industries as an SHM tool for pipes. Improvements include increased efficiency, reduced cost and increased long-term survivability of the sensor system. Transduction efficiency was increased by reducing the sensor eddy current losses and by using a field concentrator strip. For long-term monitoring, a low-cost magnetic oxide based MsS material (video recording tape) having the required magnetic properties was used. The MsS strips were oriented to generate non-dispersive torsional guided ultrasonic waves that propagate long distances with minimal mode conversion. Further, considering both safety and long-term survivability of the sensor, low-power ultrasonic instrumentation was developed and tested. Measurements reported here demonstrate the sensitivity of this sensor to both radial notches (sawcuts) and drilled holes. Results also show that magnetic anisotropy of the strip plays a role in generating torsional waves. It is envisioned that results obtained from the present study will significantly enhance the ability to monitor the long-term structural health of piping systems. © IOP Publishing Ltd.
About the journal
JournalSmart Materials and Structures
ISSN09641726
Open AccessNo
Concepts (9)
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    Elastic waves
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    MAGNETOSTRICTIVE DEVICES
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    Structural health monitoring
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    Ultrasonic waves
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    Wave propagation
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    FIELD CONCENTRATORS
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    MAGNETOSTRICTIVE TAPES
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    SENSOR EDDY CURRENT LOSSES
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    MAGNETIC TAPE