Low Speed Impact of Woven Fiber Composites Including Fiber Bragg Grating Sensors

In this paper, the dynamic Fiber Bragg Grating sensor response due to low speed impact on woven fiber composite plates was used to determine the extent of the impact damage. Three types of woven fabrics were considered in this study: plain, twill and 5 harness satin. A brief finite element analysis was used to determine the optimal location for the sensors. The bottom of the plate showed the highest strain response and was chose as the optimal location. The composite plates were fabricated and Fiber Bragg Grating sensors were mounted in the optimal location. The plates were subject to various impact energies using a modified Charpy impactor. The impact damage for each plate due to different impact energies was quantified through flash thermography and correlated with the FBG response. The flash thermography results showed excellent progression of damage in the plates and the sensor strain response was able to distinguish the impacts by considering both peak and plastic strain.