Analysis of Longitudinal Strains of Cross-ply Composite Laminates using A-EFPI Optical Fiber Sensor

Abstract

The longitudinal strains (ε_x) of the core and the skin layers in glass fiber reinforced plastic (GFRP) cross-ply composite laminates are analyzed using embedded optical fiber sensors (OFSs) of absolute extrinsic Fabry—Perot interferometer (A-EFPI). Foil-type strain gages (SGs) bonded on both upper and lower surfaces of a specimen are employed for comparison of the strain measurement on the surface. It has been shown that the values of ε_x in the interior of the skin layer and the core layer measured by embedded A-EFPI sensor are lower than those of the specimen surface measured by SGs. Experimental results agree well with those from finite element analysis based on a shear lag model. Optical microscopy observation of the damage behavior around the fiber sensor by the thin-sectioning technique shows that reinforcing glass fibers protect the OFS embedded in the 0^° skin layer, whereas the formation of transverse cracks in the 90^° core layer substantially reduces strains at the failure of OFS embedded in the core layer.

Keywords

optical fiber sensor cross-ply composite laminates shear lag model transverse crack failure.

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