Crack monitoring of tensile members in FBG sensing technology considering the strain redistribution of aluminium alloy substrates

An encapsulated optical fiber sensor based on FBG sensing technology has been developed, which can effectively monitor the cracking of Al alloy substrates. By establishing the strain transfer model, the influences of the adhesive length, adhesive width, thickness and modulus of the optical fiber sensor on the strain transfer rate are derived, providing a scientific basis for the selection of the optimal laying method. Meanwhile, considering the influence of surface cracks of the substrate on the strain distribution, an analytical model for transmitting strain from the cracks of the Al alloy substrates to the FBG sensor is proposed. A tensile test of the sensor tape on Al alloy substrates is performed, and the feasibility of the sensing tape for crack detection and identification of crack locations is demonstrated. And the test results show that the sensor tape is sensitive to the dynamic variation of strain distribution caused by changed tensile force and tensile rate. The test results demonstrate that the FBG sensing tape has advantages for monitoring cracks.