Efficient design of Fiber Optic Polarimetric Sensors for crack location and sizing

The Fiber Optic Polarimetric Sensor (FOPS) is an attractive tool for damage monitoring in structures. However the system is not capable of identifying damage location and crack size, which would further assist in the assessment of the severity of damage. Also, the output signal from FOPS is very noisy because of the fact that the whole fiber is sensitive and picks up unwanted signals from its surroundings. In the current work, a new design of FOPS has been put forward for structural health monitoring (SHM). It has been shown that in this new design, only the central part of FOPS is sensitive keeping the "leading-in" and "leading-out" parts insensitive, allowing SHM using FOPS sensitive only to the region of interest. This design is then implemented to locate and estimate the size of a crack in a cantilever. Unlike previous studies, the current approach considers second vibrational mode along with the first vibrational mode to get better understanding of the damage size and location. In this paper, the location and sizing of a crack in a cantilever beam are studied theoretically and verified experimentally. (C) 2014 Elsevier Ltd. All rights reserved.