Regenerated bragg grating sensor array for temperature measurements during an aluminum casting process

An array of regenerated fiber Bragg gratings (RFBGs) was employed to monitor the temperature distribution during an aluminum cast process. Significant temperature gradients in the cast part were observed during the cooling and solidification period. The direction and velocity of the solidification front was revealed by the temperature data obtained by the RFBGs at different measurement points. A generalized calibration curve was established and applied to the RFBG array, avoiding the need of individual calibration measurements of each sensor element of the array. Temperatures measured using the RFBGs and a thermocouple placed in a reference arm of the mold showed excellent agreements and indicated that no thermal drift of the RFBGs sensor elements occurred during the casting. The RFBG measurements were carried out with only a single fiber, which reduced the amount of lead cables in the melt and hence minimized the sensor-induced disturbances to the casting process. In addition, the limited number of cables enables the RFBG sensors to be deployed in small and complex cast geometries. Multipoint temperature sensors based on RFBG arrays can become important tools to improve the quality of casting processes.