For improving quality of a carbon fiber reinforced composite material (CFRP) by
preventing defects such as delamination and void, it should be inspected in fabrication process. Novel
non-contacting evaluation technique is required because the transducer should be contacted on the
CFRP in conventional ultrasonic technique during the non-destructive evaluation and these
conventional contact techniques can not be applied in a novel fiber placement system. For the
non-destructive evaluation of delamination in CFRP, various methods for the generation and
reception of laser-generated ultrasound are applied using piezoelectric transducer, air-coupled
transducer, wavelet transform technique etc. The high frequency component of laser-generated
guided wave received with piezoelectric sensor disappeared after propagating through delamination
region. Air-coupled transducer was tried to be adopted in reception of laser-generated guided wave
generated by using linear slit array in order to generate high frequency guided wave with a frequency
of 1.1 MHz. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled
transducer and linear slit array. Transmitted laser-generated ultrasonic wave was received on
back-wall and its frequency was analyzed to establish inspecting technique to detect delamination by
non-contact ultrasonic method. In a frequency spectrum analysis, intensity ratio of low frequency and
center frequency was approvable parameter to detect delamination.
Polarimetric SAR Image Classification with High Frequency Component Derived from Wavelet Multi Resolution Analysis: MRA
