3D Printing of a miniature turbine blade model with an embedded fibre Bragg grating sensor for high-temperature monitoring

Rapid advances in 3D printing enable the construction of complex metal structures. However, sensor embedding within 3D printed metal structures has been challenging due to its extremely high-temperature condition. Here, we embedded an optical fibre sensor for temperature monitoring within a Ni-alloy miniature turbine blade by directed energy deposition (DED) printing. To endure the high-temperature condition, a fibre Bragg grating (FBG) sensor was electroplated with a Ni layer, and various 3D printing parameters were optimised. In particular, to minimise the accumulation of thermal energy in the FBG sensor, ‘line-by-line printing and stop’ process was applied around the sensor. The embedded sensor accurately measured temperature cycling up to 500°C with the sensitivities of 28.3 and 27.2 pm/K in heating and cooling cycles, respectively. Finally, an FBG sensor was successfully embedded in a miniature turbine blade by our DED process, demonstrating its feasibility for high-temperature monitoring.