Thermal Behavior of Metal Embedded Fiber Bragg Grating Sensor

With embedded sensors, the structures are capable of monitoring parameters at such critical locations not accessible to ordinary sensors. Recently, fiber optic sensor emerges as one promising technology to be integrated with structures. Embedding of fiber optic sensors into composites and some metals, especially those with low melting points, have been reported. However, all reported embedding techniques so far are either complicated or difficult to achieve coherent bonding with low residue stresses. Thus, it is of strong interest to pursue some economical ways to embed fiber optic sensors into metallic structures with low residue stresses. In this work, a new technique is proposed for embedding fiber optic sensor into metallic structures, such as nickel, with minimized residue stress. Fiber Bragg Grating (FBG) sensors have been embedded into nickel structures. Thermal performance of such embedded FBG sensor is studied. Higher temperature sensitivity is demonstrated for the embedded FBG sensors. For temperature measurements, the embedded FBG sensor yields an accuracy of about 2 °C. Under rapid temperature changes, it is found that thermal stresses due to the temperature gradient in the metallic structures would be the main cause for errors.