A new approach for estimation of damage patterns in CFRP composite laminates using embedded FBG sensors

This paper proposes a new approach to estimate the damage pattern of a notched cross-ply laminate using an embedded Fiber Bragg Grating (FBG) sensor. The damage pattern near the notch was investigated by finite element analysis with cohesive elements for the onset and the extension of various cracks. Then, the reflection spectrum of the FBG sensor was analyzed from the strain distribution obtained in the damage analysis. Based on the above analysis, the damage pattern is optimized as an inverse problem in the damage analysis, while the spectrum shape is adopted as the objective function. In the estimation scheme, the strain distribution of the FBG sensor is calculated by the damage analysis using the damage pattern expressed by the residual strength distribution of the cohesive elements. We estimated the damage patterns of the notched cross-ply laminate from the reflection spectra obtained in the analysis and those measured in the experiment. The estimated damage patterns agreed well with those corresponding to the input spectra.