Fabrication and evaluation of hybrid silica/polymer optical fiber sensors for large strain measurement

Abstract

Silica-based optical fiber sensors are widely used in structural health monitoring systems for strain and deflection measurement. One drawback of silica-based optical fiber sensors is their low strain toughness. In general, silica-based optical fiber sensors can only reliably measure strains up to 2%. Recently, polymer optical fiber sensors have been employed to measure large strain and deflection. Due to their high optical losses, the length of the polymer optical fibers is limited to 100 meters. In this paper, we present a novel economical technique to fabricate hybrid silica/polymer optical fiber strain sensors for large strain measurement. First, stress analysis of a surface-mounted optical fiber sensor is performed to understand the load distribution between the host structure and the optical fiber in relation to their mechanical properties. Next, the procedure of fabricating a polymer sensing element between two optical fibers is explained. The experimental set-up and the components used in the fabrication process are described in details. Mechanical testing results of the fabricated silica/polymer optical fiber strain sensor are presented.

Self-repairing waveguide sensor with highly repeatable strain response

“…[4][5][6][7] Previous researchers have demonstrated self-writing waveguides applied to the sensor to measure vibration and strain. [8][9][10] These results demonstrated the potential of self-written polymer waveguide sensors, however repeatability and cyclic behavior of the sensor response during the loading and unloading cycles were not addressed. The authors previously created a self-repairing strain sensor based on a self-written polymer waveguide between two silica optical fibers.…”

Self-repairing polymer optical fiber sensor

“…Previous researchers have measured optical power losses through self-writing waveguides and applied these to strain measurements. [5][6][7][8][9] These results demonstrate the potential of self-written polymer waveguide sensors, however issues such as repeatability, durability and cyclic behavior were not addressed.…”

Finite element formulation for self-writing of polymer optical fiber sensors

“…A more recent sensor design, applicable to structural health monitoring appli-cations, was developed by Huang [20]. Huang grew a polymer sensing element between two multimode silica fibers for use as an intensity-based strain sensor.…”

“…The following chapter will present the theory behind the model development based on the optical, chemical and mechanical processes. Chapter 4 will present the simulation results, their comparison with previous experimental data and an extrapolation of the original model to demonstrate the curing process of a polymer sensing element between two silica fibers similar to the sensor developed by [20]. Finally, Chapter 5 will summarize the results and propose future directions for the model.…”