Temporary Fiber Bragg Grating Sensors for Static and Dynamic Strain Measurements in Hypersonic Wind Tunnels

Abstract

This paper reports on the results of a preliminary investigation into three different adhesive tapes – Washi acrylic masking, high-temperature fiberglass backed aluminum, and double-sided acrylic tissue - for temporarily bonding Fiber Bragg Gratings (FBGs) to a metallic substrate. The development and analysis of suitable temporary adhesives allows for rapid testing and conservation of expensive optical componentry in hypersonic wind tunnel tests. Tensile testing was undertaken wherein force and displacement values are recorded. A Thorlabs S5FC1005S Super Luminescent Diode (SLED) is used to illuminate the FBG following which a Photonetics WALICS Optical Spectrum Analyzer (OSA) is utilized to obtain the reflected optical spectrum. The shift in spectrum is analyzed using a Generalized Cross-Correlation (GCC) and compared to measured strain values to determine the sensitivity and linearity of the FBG response for each of the adhesives. It was found that all tapes resulted in low strain efficiencies but relatively linear responses.