Improved Thermal Signature of Composite Beams with GNP Smart Skin for Defect Investigation

In this paper, it is aimed to identify flaws in glass fiber reinforced polymer composites by smart skin graphene nano platelet (GNP) spray coating in infrared thermography technique. The initial resistance of GNP was made to 1 kΩ. Characterization of sensor and beam was done with scanning electron microscopy and computed tomography (CT) respectively. The thermo-elastic behaviour was evaluated in uniaxial test. The surface temperature was studied with IR camera and it was observed that the surface coated GNP sensor upon a damage and without the damage specimen retains heat than without coating the sensor. Hereafter testing with 0.1 mm/min, 0.5 mm/min and 1 mm/min, it was found that without damage specimen, the temperature increased to 112.5%, 13.3% and 40% respectively. And temperature increased to 93.2%, 36.7% and 76.4% in the specimen with the damage. Specimen were also tested for spectrum fatigue cyclic load at 0.1 Hz and 1 Hz. Failure peak of laminates has been analyzed with optical microscopy and CT which was correlated with temperature rise. For 0.1 Hz spectrum loading, the specimen with the damage, with and without GNP coated, temperature rose to 2040% after first laminate failure. Similarly, for 0.1 Hz specimen temperature rose to 15,637.5% in case of without damage specimen, with GNP coated than without GNP coated. And in case of 1 Hz spectrum loading with damage specimen, the temperature rose to 105.73% after GNP coated. Similarly, at 1 Hz loading, the temperature rose to 143.07% in case of without damage specimen after GNP coated. GNP skin coated nano-sensor helps in early detection of temperature signals.