Study on Evaluating Damage of CFRP Using the PVDF Comb Transducer

Recently, fiber reinforced plastic (FRP) materials become to be used more in producing airplanes because of high specific strength and low weight. However, there can be delamination caused from unexpected impact during the service flight. Since strength reduce comes with these delamination defects, defects in the composite materials should be monitored for safety of the airplane. A PVDF transducer can be used for on-line health monitoring economically. In this study, comb type of PVDF transducer was fabricated for generating and receiving of the guided wave at specific wavelength and was applied to evaluate natural delamination defect with the guided wave. Natural delamination in CFRP was produced with free dropping weight on CFRP surface between the transmitter and the receiver transducers. At every impacts, guided wave was generated and received in the pitch-catch way with the PVDF(Polyvinylidene fluoride) comb transducer and variation of the guided wave signal was compared according to accumulation of impact damage.