Monitoring of liquid composite molding parameters based on FBG-FP sensor

The liquid composite molding process is a common composite manufacturing method, while the real-time monitoring and control of the manufacturing parameters remain challenging, affecting product quality and efficiency. Optical fiber sensors offer distinct advantages including minimal impact on composite properties and high monitoring sensitivity. This study established an all-fiber monitoring system integrating fiber Bragg grating (FBG) and Fabry-Perot (FP) sensors to simultaneously track the internal temperature and strain, detect resin flow front during injection and curing processes. Results showed that the optical fiber sensors system achieved flow front monitoring within 10% accuracy, enabled 3D flow tracking in thick composites, and identified critical flow arrivals at the interfaces between the sandwich panel and core. Temperature measurements aligned with thermocouple data (<2℃ error), while revealing curing temperature-strain inhomogeneity and capturing key parameters like gel points and curing-induced strains.