Strain Monitoring and Damage Detection of a Filament Wound Composite Pressure Tank using Embedded Fiber Bragg Grating Sensors

Abstract

Composite pressure tanks are rapidly expanding in their range of use. However, for high pressure flammable or toxic gases, there is less confidence about their reliability. In this study, fiber Bragg grating (FBG) sensors embedded into a filament wound composite pressure tank monitored strain and detected damage. The sensor heads and fiber optic lines were protected with an acrylate recoating, adhesive films, and PVC tubes with Teflon® to survive under the harsh environment of the filament winding process. During the quasi-static loading test, the internal strain was measured with embedded FBG sensor arrays. Simultaneously, acoustic emission (AE) signals from matrix cracks and delaminations were detected with both an embedded FBG sensor and an attached piezoelectric sensor. The signal characteristics from the sensors were then compared. For the feasibility test of active sensing, impacts were applied on 3 different positions in each side by an impact hammer. The difference between damaged and undamaged sides in impact response was analyzed. A FBG interrogation system using a wavelength-swept fiber laser (WSFL) was used for the strain measurement, and an EDFA source with a tunable Fabry-Perot filter was used for the high frequency vibration.