Damage detection method of CFRP structure based on fiber Bragg grating and principal component analysis

Damage detection is very important to ensure the safety of carbon fiber reinforced plastics (CFRP) structure. In this paper, a damage detection method of composite structure based on fiber Bragg grating sensors and principal component analysis was proposed. Firstly, the non-damaged CFRP structure was excited by active excitation, and its dynamic response signal was monitored by FBG sensors. The FBG sensors were attached to the surface of the CFRP structure. And then, the frequency response was extracted as the damage feature by using the Fourier transform method. After that, principal component analysis was used to reduce the dimension of damage feature. The principal component model of the non-damaged state only based on the non-damaged state samples was established and the reconstruction error threshold was determined as the index of damage detection. Thus, structural damage can be detected by determining if the reconstruction error of the new sample was greater than the reconstruction error threshold. Finally, the damage detection system of CFRP structure was constructed to validate the proposed method. The experimental results showed that the method proposed in this paper can accurately identify whether the structure was damaged only based on the non-damaged state samples. This paper provided a feasible method for the damage detection of CFRP structure.