Estimation of the damage patterns in notched laminates with embedded FBG sensors

This study proposes a new method to estimate the damage patterns of notched composite laminates as an inverse problem using the reflection spectrum of embedded Fiber Bragg Grating (FBG) sensors. The damage pattern near the notch is analyzed by a layer-wise finite element model with cohesive elements to represent various cracks. The reflection spectrum of the FBG sensor is then analyzed from the strain distribution obtained in the damage analysis. The damage pattern is optimized as an inverse problem based on the above analyses while the spectrum shape is adopted as the objective function. The damage pattern is expressed by the residual strength distribution of the cohesive elements in the estimation scheme. The applied strain is also estimated by the wavelength shift of the reflection spectrum. The damage pattern and the applied strain estimated from the measured spectrum are found to agree with the experimental results.