Detection of delamination in composite laminates using small-diameter FBG sensors

Shin-ichi Takeda; Yoji Okabe; Nobuo Takeda

doi:10.1117/12.472611

27 June 2002 Detection of delamination in composite laminates using small-diameter FBG sensors

Shin-ichi Takeda, Yoji Okabe, Nobuo Takeda

Proceedings Volume 4694, Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems; (2002) https://doi.org/10.1117/12.472611
Event: SPIE's 9th Annual International Symposium on Smart Structures and Materials, 2002, San Diego, California, United States

Abstract

This paper presents delamination monitoring techniques in composite laminates using small-diameter fiber Bragg grating (FBG) sensors that was developed for embedding in the laminates without inducing any structural defects. First, this FBG sensor was embedded in carbon fiber reinforced plastic (CFRP) cross-ply laminates. The reflection spectra from the FBG sensor were measured at various delamination sizes through a static four-point bending test. From experimental results, the spectrum was found to have two peaks due to the initiation of the delamination. The intensity ratio of these two peaks changed as the delamination size increased. In order to confirm the deformation of the measured spectra, the spectra were calculated theoretically. The calculated result reproduced the change in the measured spectrum very well. Thus, we proposed the intensity ratio of the two peaks as an effective indicator for evaluation of the delamination size. Secondly, detection of the edge delamination in quasi-isotropic CFRP laminates was conducted using the FBG sensor. The reflection spectra were measured at various delamination sizes through fatigue test. The form of the spectrum changed sensitively by growth of the edge delamination. Hence the small-diameter FBG sensor could also be applied to detect the edge delamination in quasi-isotropic composite laminates under cyclic loading.

Citation Download Citation

Shin-ichi Takeda, Yoji Okabe, and Nobuo Takeda "Detection of delamination in composite laminates using small-diameter FBG sensors", Proc. SPIE 4694, Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems, (27 June 2002); https://doi.org/10.1117/12.472611

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