Event Title

Pulsed Eddy-Current Interaction with Subsurface Cracks

Presenter Information

J. R. Bowler, University of Surrey

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Calculations have been carried out to evaluate pulsed eddy-current interaction with a planar crack in a conductor. The field is excited by a coil carrying current pulses while crack signals are detected by measuring changes in the magnetic field above the conductor or by monitoring variations in the induced emf across the coil. An integral formulation of the problem has been used to determine the field at the surface of the crack as a function of time. A discrete matrix approximation of the integral equation is derived based on the moment method. Using a time-stepping procedure, the matrix equation is solved to obtain the field at a specific time using the solutions at all previous time steps starting at the initiation of the excitation pulse. The signal detected by a magnetic field sensor on the axis of the coil is then computed.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 2: Electromagnetic, Thermal, and X-Ray Techniques

Section

John Moulder Memorial Session/Eddy Currents

Pages

477-483

DOI

10.1007/978-1-4615-4791-4_60

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Pulsed Eddy-Current Interaction with Subsurface Cracks

Snowbird, UT, USA

Calculations have been carried out to evaluate pulsed eddy-current interaction with a planar crack in a conductor. The field is excited by a coil carrying current pulses while crack signals are detected by measuring changes in the magnetic field above the conductor or by monitoring variations in the induced emf across the coil. An integral formulation of the problem has been used to determine the field at the surface of the crack as a function of time. A discrete matrix approximation of the integral equation is derived based on the moment method. Using a time-stepping procedure, the matrix equation is solved to obtain the field at a specific time using the solutions at all previous time steps starting at the initiation of the excitation pulse. The signal detected by a magnetic field sensor on the axis of the coil is then computed.