Dynamic Feature Identification of Carbon-Fiber-Reinforced Polymer Laminates Based on Fiber Bragg Grating Sensing Technology

Carbon-fiber-reinforced polymer (CFRP) composites have many advantages, and have been widely used in aerospace structures, buildings, bridges, etc. The analysis of dynamic response characteristics of CFRP composite structures is of great significance for promoting the development of smart composite structures. For this reason, vibration experiments of CFRP laminates with surface-attached fiber Bragg grating (FBG) sensors under various dynamic loading conditions were carried out. Time- and frequency-domain analyses were conducted on the FBG testing signals to check the dynamic characteristics of the CFRP structure and the sensing performance of the installed sensors. The results show that the FBG sensors attached to the surface of the CFRP laminates can accurately measure the dynamic response and determine the excited position of the CFRP laminates, as well as invert the strain distribution of the CFRP laminates through the FBG sensors at different positions. By performing Fourier transform, short-time Fourier transform, and frequency domain decomposition (FDD) on the FBG sensing signals, the time–frequency information and the first eight modal frequencies of the excited CFRP structure can be obtained. The modal frequencies obtained by different excitation types are similar, which can be used for structural damage identification. The research in this paper clarifies the effectiveness and accuracy of FBG sensors in sensing the dynamic characteristics of CFRP structures, which can be used for performance evaluation of CFRP structures and will effectively promote the design and development of intelligent composite material structures.