Fiber Bragg grating monitoring for composites in the out-of-autoclave curing process

Temperature and strain are two of the most significant parameters in the curing process of composites. Fabrication of a strain-free temperature sensor has been completed by encapsulating a fiber Bragg grating (FBG) in a capillary ceramic tube. The grating string composed of a bare grating and an encapsulated grating has been embedded in the composites. The temperature and strain of the out-of-autoclave curing process have been monitored. In addition, the accuracy of the temperature monitoring has been proved by comparing the temperature monitoring results with common gratings, high temperature-resistant gratings, and thermocouples. It is found that the high temperature-resistant gratings are more suitable for the composite curing process, especially for the monitoring of the out-of-autoclave curing process at an internal high temperature. This study provides a reference for multiparameter monitoring by using gratings in the out-of-autoclave curing process of composites.