Design and Development of SMA coated optical fiber sensor for condition monitoring

Abstract

The work focuses on the development of copper-based and Nickel based shape memory alloy (SMA) coated optical fiber sensor. These sensors have potential applications towards condition monitoring in different systems. The Cu-Al-Ni (82%-14%-4%) and Ni-Ti (50%-50%) SMA has been deposited on optical fiber using flash evaporation. For efficient deposition an in-situ fixture had been designed, which has a capability to induce strain and rotate the fiber to get uniform coating. The samples are prepared by varying the fixture rotational speed between 24 to 36 rpm. The deposition at 24 rpm speed has achieved maximum bending angle of 59.1º and 42º. The austenite phase transformation has confirmed at 231.15º C and 122˚C using differential scanning calorimeter. The actuation behaviour has been investigated in detail for varying load and voltage. A maximum deflection of 3.7 mm for CuAlNi coated fiber and 2.25 mm for NiTi coated fiber was achieved at 3 V against 25 mg and 35 mg load. In addition, the surface morphology, thickness measurement and thermal analysis of coated and uncoated optical fiber have been investigated in detail. Also sensing characteristics of the coated optic fiber using time vs temperature plot has been analysed using thermal camera. In this work, sensor characteristic-based parameters (response time and sensitivity) were also calculated.