Electrical resistivity has been used to detect the internal damage in glass
fibre-polyester composite sheet materials. It is shown that the introducti
on of microstructural damage to the composite increases the electrical resi
stivity in a direction perpendicular to the plane in which the fibres lie.
In these experiments, the samples were subjected to some predetermined valu
e of impact energy using a drop weight tester. The impact energy causes fib
re-matrix debonding and microcrack propagation within the matrix and fibres
. The measurement of the electrical resistivity before and after impact rev
eals a linear relation between the electrical resistivity and the magnitude
of the applied impact energy. The reproducibility of the data was higher (
within +/-2%) for the less damaged samples. For the more severely samples,
however, the reproducibility was poorer (within +/-8%). This is a good feat
ure, as the extent of damage in the less severely damaged samples cannot be
detected by visual inspection.