Detection of impact damages in CFRP laminates with small-diameter FBG sensors

摘要

This paper presents the application of small-diameter fiber Bragg grating (FBG) sensors for the monitoring of the damage induced by low-velocity impact. The FBG sensors were embedded into carbon fiber reinforced plastic (CFRP) laminates [0{sub}4/90{sub}2]{sub}s. Using a drop-weight impact tester, an impact loading was applied to the laminates at three impact energy levels. The reflection spectra from the embedded FBG sensors were measured after the impact tests. The delamination that appeared inside the laminates was observed by ultrasonic C-scan. The form of the reflection spectrum changed sensitively depending on the delamination size. Furthermore, the spectra were calculated theoretically for confirmation of the measured spectra. The change in the form of the measured spectrum was consistent with that of the calculated spectrum. From these results, the reflection spectrum was found to be a good indicator for evaluation of the delamination size induced by the low-velocity impact.