Renewable energy sources have gained much attention due to the recent energy crisis and the urge to get clean energy. Among the main options being studied, wind energy is a strong contender because of its reliability due to the maturity of the technology, good infrastructure and relative cost competitiveness. In order to harvest wind energy more efficiently, the size of wind turbines has become physically larger, making maintenance and repair works difficult. In order to improve safety considerations, to minimize down time, to lower the frequency of sudden breakdowns and associated huge maintenance and logistic costs and to provide reliable power generation, the wind turbines must be monitored from time to time to ensure that they are in good condition. Among all the monitoring systems, the structural health monitoring (SHM) system is of primary importance because it is the structure that provides the integrity of the system. SHM systems and the related non-destructive test and evaluation methods are discussed in this review. As many of the methods function on local damage, the types of damage that occur commonly in relation to wind turbines, as well as the damage hot spots, are also included in this review.
In this paper, we present the simultaneous measurement
of the strain and temperature during cures of various composite
laminates using fiber Bragg grating/extrinsic Fabry-Perot
interferometric (FBG/EFPI) hybrid sensors. The characteristic
matrix of the hybrid sensor is derived analytically. For the
fabrication of the three types of graphite/epoxy composite
laminate, two FBG/EFPI hybrid sensors were embedded in each
composite laminate in two mutually perpendicular
directions. We performed the real-time measurement of
fabrication strains and temperatures at two points within the
composite laminates during the curing process in an autoclave. Through
these experiments, FBG/EFPI sensors are proven to be a
good choice for efficient smart monitoring of composite structures.
In this paper, a novel technique for the simultaneous
measurement of strain, temperature and vibration for
structural health monitoring is demonstrated using a fibre
optic sensor system, which combines both a
wavelength-swept fibre laser (WSFL)
system and a laser diode system using a
wavelength division multiplexer. An aluminium beam was placed in
a thermal chamber for the simultaneous measurement of its
strain, temperature and vibration characteristics. A fibre
Bragg grating/extrinsic Fabry-Perot interferometer (EFPI)
hybrid sensor system with WSFL was used for the strain and
temperature measurements, while the EFPI sensor in the hybrid
sensor operated by a laser diode simultaneously measured the
vibration characteristics of the beam.
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