Evaluation of a Novel Eddy-Current Probe for Detecting Cracks Inside and at the Edges of Holes

Preliminary studies performed during a previous investigation at SRI showed that a modified floppy-disk tape head operating at 100 kHz is a very sensitive crack detector. For example, tests on 0.25-in.-long fatigue cracks in aluminum produced signals an order of magnitude larger than those obtained using a commercial 100-kHz coil probe. The floppy-disk probe contains ferrite material, but its construction is different from other ferrite-containing eddy-current probes