Development and characterization of fibre bragg grating sensor packaging for aircraft structural health monitoring applications

The use of fibre optic sensors for structural health monitoring (SHM) has been persuaded by the aircraft industry and research organizations for over three decades. The Fibre Bragg Grating (FBG) sensors, because of their inherent advantages, are considered the best choice for the aircraft industry for structural health monitoring applications. These sensors are fragile in nature and are still being used in lab-scale experiments. A methodology is developed to package the sensors using a glass-carbon/epoxy composite to make the sensor robust without altering its sensitivity. Different arrangements are established for the protection of the sensing region and the non-sensing region of the sensor. Sensor packaging is carried out in such a way that the sensor quality and its strain transfer capability are unaltered. Based on spectrum comparison and ease of installation, the sensing region of FBG is packaged between composite layers, and the non-sensing region is protected using Teflon and other flexible tubes. The temperature and strain response of the sensors are studied experimentally and compared with bare FBG sensor and resistance strain gauge (RSG) respectively. These studies showed that packaging has the same response to strain and temperature and is very reliable.