Low-velocity impact damage monitoring of composite T-stiffened panels based on FBG sensors

Fiber Bragg grating(FBG) sensors were embedded in triangle region of carbon fiber reinforced epoxy composite T-stiffened panels to real-time monitor the strain change during impact. By embedding the FBG sensors in the composite laminates and triangle region of the T-stiffened composite plates respectively, the effects of FBG sensors on the properties of the composite laminates and T-stiffened composite plates were studied. The results show that the tensile strength of the composite laminates with FBG sensors can be about 5% lower than the laminates without FBG sensors. Within the failure strain scope of FBG sensors, the FBG sensors could accurately monitor the strain signals real-time for the composite laminates. The compressive load of the T-stiffened panels with FBG sensors in triangle area is almost same as the T-stiffened panels without FBG sensors. Moreover, the effects of impact location and impact energy on the impact time and max-strain measured by the FBG sensors were studied. The results show that the impact time is increased with increasing impact energy. However, the max-strain is decreased with increasing impact distance, increased with increasing impact energy. By embedding the FBG sensors in triangle area of the composite T-stiffened panels, the impact location and impact energy of the composite T-stiffened panels could be monitored real-time by FBG sensors preliminarily.