In this paper, the vibration performance and damage types of carbon fiber composite materials were investigated based on FBG sensing technology. The free end of a carbon fiber composite cantilever beam was hit by a falling ball to generate a resonance in the cantilever. The resonance frequency was measured and the damping loss factor was calculated based on which the vibration characteristic of the carbon fiber composite was analyzed. After that, a man-made damage (a small hole) was introduced into the cantilever and the resonance frequency was measured again. The result was compared with the frequency without damage, so that the damage type could be judged. The result provides a reference to the study of the vibration performance and damage monitoring of carbon fiber composite materials.
A fiber Bragg grating (FBG) sensing network with a bus chain typology structure based on time-division multiplexing (TDM) technology has been developed. Each FBG sensor was placed in an isolated branching circuit separated by an optical splitter. By doing this, multiple reflection and spectrum shadow, which are common in a traditional TDM network, were eliminated since incident light reflected by each sensor did not go through the other sensors. Interference among different FBGs was also avoided. The system was experimentally verified by constructing such a network with 17 FBGs involved. Wavelength and position interrogation were successfully realized. Temperature experiment was carried out on four of the FBGs and the sensitivity was 9.87, 9.92, 9.91, and 9.97 pm/°C, respectively. The durability, reliability, and measuring accuracy of the sensing network were effectively improved due to the bus chain typology structure.