In-situ temperature and strain during copper casting process were monitored for the first time based on regenerated fiber Bragg grating (RFBG) sensors, with the maximum temperature up to 1100 $^{\circ }$ C and the largest compressive strain approximately −14 000 $\mu$ $\varepsilon$ . A generalized fifth-order polynomial calibration function was used to convert the measured Bragg wavelengths from RFBG into temperature values. With an RFBG temperature sensor array, the temperature distribution as a function of time was obtained, revealing how the temperature gradient changed during the casting process. In-situ strain was measured by an RFBG strain sensor in direct contact with copper, showing the strain progression inside the copper at different temperatures during the casting. The RFBG-based in-situ monitoring method provides a new way for measuring multiple parameters in high temperature casting, which can be used for improving the design of the casting mold and upgrading the casting quality. Furthermore, our investigation lays a good foundation for fiber-embedded smart metal structures as it shows that fiber sensors can be embedded in copper casts without special surface treatment.

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.