Abstract
Carbon fiber reinforced plastics (CFRPs) are generally used for weight reduction of industrial structures. Highly strong reinforced plastics and highly rigid matrixes in CFRP consist CFRP′s high performance (e.g. specific strength and rigidity), while CFRP can be defected inside (e.g. deferent material interface or interlaminar) by off-plate directional impact load easily to reduce their strength significantly. Therefore, periodical non-destructive testing (NDT) is required for maintenance of their integrity. In addition, CFRP has remarkable mechanical and electrical anisotropy; especially electrical resistances are approximately 1000 times different between longitudinal and orthogonal direction. In this study, we propose new thermography method for CFRP delamination detection with electrical resistance heating of intentionally selected layer by using above-mentioned CFRP′s electrical resistance anisotropy (selective-layer heating). This method can detect the delamination crack induced in an objective more deeply than the other thermography method that excite heat from an objective surface and can determine the delamination depth more precisely by excluding influence of 3-dimensional heat conduction than the other thermography method.
