FBG fracture monitoring for CFRP based on coupling characteristic of modulus/strain wave

From the sensitivity of the fibre Bragg grating (FBG) center wavelength changing with strain changes on the surface of carbon fibre reinforced plastics (CFRP) composite, the correlation between the tensile rate of the FBG wavelength and the fracture status was investigated during the stretching process and the strain wave response characteristics of the specimen surface, that is, the elastic modulus of CFRP tensile specimens decreases with the increasing of the internal damage, and stabilizes before the appearance of the stress relaxation in the specimen, at which the strain response of acoustic emission received on the surface of the fracture area is slightly greater than the one in other areas. By combining FBG with the CFRP fracture monitoring, a CFRP fracture monitoring method based on the FBG has been proposed. The method coupling sensing probe directly with specimen has achieved the absolute monitoring of CFRP fracture state.