N. Nakagawa, S. J. Lee, C. Lee, C. Lo, Iowa State University, Ames, IA
Eddy current (EC) NDE modeling can be useful in improving and optimizing performance of EC instrumentation. However, to apply any model-predicted signals to a given instrument, one must understand the relationship, or the system transfer function, that relates instrument output signals to predicted signals. This paper reports on a system transfer function determination for a proprietary pulsed eddy current (PEC) instrument, based on the analytical Cheng-Dodd-Deeds model. Specifically, measured PEC waveforms taken with generalized half-space samples are compared with model-predicted waveforms in frequency domain, leading to the determination of the PEC instrument transfer function. We present studies of half-space and layered samples in various material combinations, so that we not only determine the transfer function but also validate it among the variety of the sample configurations. We plan to present PEC waveforms for defect specimens as well, namely both instrument and converted waveforms.
This work was performed at the Center for NDE at Iowa State University with funding from the Air Force Research Laboratory through S&K Technologies, Inc. on delivery order number 5007-IOWA-001 of the prime contract F09650-00-D-0018.
Summary: This paper reports on a system transfer function determination for a proprietary pulsed eddy current (PEC) instrument, based on the analytical Cheng-Dodd-Deeds model. By this work, we demonstrate a utility of NDE modeling for characterizing NDE instrumentation.
