Characterization of Spectral Response of a FBG Sensor Embedded in a Metallic Structure Using Laser Solid Freeform Fabrication

Abstract

This paper focuses on spectral response characterization of fiber Bragg grating (FBG) sensors embedded in metallic structures using laser solid freeform fabrication (LSFF). Fiber Bragg grating sensors are capable of measuring temperature, strain and pressure and can be embedded in metallic structures to monitor thermal and structural loads. Due to the sensitivity of the FBG sensors to high temperatures and stresses, the embedding process using LSFF is a challenging task. In the present work, a finite element model is developed to predict the stress and temperature fields adjacent to the fiber optic sensor embedded the metallic structure. The FE results are transferred to opto-mechanical model of the FBG sensor to predict the change in the spectral response of the sensor. Finally, the finite element model is verified using an existing analytical model which predicts the temperature field and melt pool geometry in LSFF process.