Strain and temperature monitoring of asymmetric composite laminate using FBG hybrid sensors

Fiber Bragg grating (FBG) hybrid sensors and thermocouples measure strain and temperature simultaneously during and after cure of asymmetric cross-ply composite laminates. FBG strain sensor is used to measure strain; FBG temperature sensor and thermocouple are used to measure temperature. The characteristic matrix of the sensor is derived analytically and measurements can be done without sensor calibration experiments. A wavelength-swept fiber laser is used as the light source. Two FBG hybrid sensors and two K-type thermocouples are embedded in a carbon/epoxy asymmetric cross-ply composite laminate in different directions and different locations. The real-time measurement of fabrication strains and temperatures is performed at two points within the asymmetric composite laminate during the cure process in a hot press. Through these experiments, FBG hybrid sensors are proven to be an efficient choice for smart monitoring of composite structures.