ISSN:
1573-4862
Keywords:
Eddy current
;
instrumentation
;
probe design
;
crack detection
;
ferritic steel
;
offshore
;
NDE
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Mathematics
Notes:
Abstract The detection and sizing of fatigue cracks in ferritic materials, especially in offshore structures, is of major importance. This paper describes an eddy current system to detect such cracks, operating in an offshore environment with a search probe to electronic instrument separation of up to 600 m. An analysis of the various factors influencing the search coil behavior is given in terms of a mutually coupled primary and secondary electrical circuit; the component values of which are influenced by the coil design, induced electrical currents in the material, and any defects it contains. It is further shown that, with proper coil parameters, the phase variation in the phase angle of the coil complex impedance can be kept almost constant compared with the rapid variation occurring during lift-off. This behavior can be exploited in the instrumentation to give a clear vector display indication of the crack presence on less than ideal surfaces.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00566222
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