Recently there has been an increasing interest in the use
of composite materials, such as carbon fiber reinforced
plastic (CFRP) in the aerospace, automobile and other
energy industries due to their thermal properties, tensile
and compression strength. However, CFRPs are very
vulnerable to the small impacts, due to their complex
structural properties, it is significantly important to detect
defects in the composite materials before it leads to
failure. In the present study an eddy current testing (ECT)
system has been developed to detect the defects in CFRP.
A differential ECT probe has been proposed, which
consists of an excitation coil and two detection coils. The
amplitude of differential voltage has been obtained from
the detection coils as the probe response. In order to test
the detectability of the probe, an artificial impact defect
was created in the test specimen. The probe has been fixed
to an x-y scanning system in order to scan a specified area
on the tested specimen. The amplitude of the differential
induced voltage was measured from the probe at each
scanning position and the images of the defect were
obtained from the test specimen. The experimental results
show that the proposed system is capable and applicable
for the testing of composite materials.